Back pain; Muscles felt really tightened up and stiff when getting out of bed and throughout the day (worst complaint); slight nausea/nausea; slight fatigue; slight headache; slightly stiff neck; right arm pain; The muscles knot up under her rib cage/muscle tightness; This is a spontaneous report from a contactable other health care professional.  A 62-year-old female patient received the first dose of the bnt162b2 (PFIZER-BIONTECH COVID-19 MRNA VACCINE; Lot Number: EL1284), intramuscularly in the left arm on 29Dec2020 at 06:30 at a single dose for COVID-19 immunization.  Medical history included Hashimoto's thyroiditis from an unknown date and unknown if ongoing.  Concomitant medications included ergocalciferol (VIT D), levothyroxine (MANUFACTURER UNKNOWN); both taken for an unspecified indication from an unspecified date to an unspecified date.  The patient previously took sulfamethoxazole and trimethoprim (BACTRIM) and experienced allergy from an unspecified date to an unspecified date, influenza vaccine (FLU VACCINE) for an immunization on an unspecified date (received within two weeks of vaccination).  The patient experienced the following events and outcomes: muscles felt really tightened up and stiff when getting out of bed and throughout the day (worst complaint) (non-serious) on 30Dec2020 at 07:00 with outcome of not recovered, slight nausea/nausea (non-serious) on 30Dec2020 at 07:00 with outcome of not recovered, slight fatigue (non-serious) on 30Dec2020 at 07:00 with outcome of not recovered, slight headache (non-serious) on 30Dec2020 at 07:00 with outcome of not recovered, slightly stiff neck (non-serious) on 30Dec2020 at 07:00 with outcome of not recovered, right arm pain (non-serious) on 30Dec2020 with outcome of unknown, back pain (non-serious) on 31Dec2020 with outcome of unknown, the muscles knot up under her rib cage/muscle tightness (non-serious) in Dec2020 with outcome of unknown.  The patient received the COVID-19 vaccine on 29Dec2020 at work, and she had been experiencing adverse events since. The worst side effect she was experiencing was muscle tightness. At the time of the report, the patient got up at 09:00, and her "back was killing her." The patient was achy. The patient would tighten up really tight under both rib cages, and it made her nauseous. The patient had been taking ibuprofen (ADVIL) and ibuprofen (MANUFACTURER UNKNOWN since she received the vaccination. The patient received the vaccine in her left arm, but her right arm hurt the next day. The next day after that (30Dec2020) she woke up and the right side of her back around the kidney area hurt. It was the right side lumbar. The next morning after that, "her entire back was killing her down the middle of her spine. From her head all the way down." Since then, it came and went. The patient could not say if it was persisting, improving or worsening for any of the symptoms. "It just grabs her." The day before the report, the patient thought she was doing better. The patient cleaned the house, and then sat down to eat. The past two nights, it had "hit her really hard during supper time." Both of her sides of her back would tighten up; "tense up like waiting for an impact before a wreck." The patient's back would seize up. The patient could not get comfortable; and would start pacing. Then, she would try to lay down. Last night, it took a half an hour to loosen back up. "It knots up like crazy. It was bad enough, she thought she was going to pass out." The patient did not know if it was the combination of eating supper or what. The patient thought if she got up that maybe she would feel better. The patient started pacing around. The patient went outside because she thought maybe fresh air would help. When it would tighten up under her rib cage, it made her nauseous. The patient did not know if it was a "vagus nerve thing or what." The patient was close to throwing up. The muscles knot up under her rib cage. The patient's back felt like she fell off a horse. It was weird to her that her left arm never bothered her. "Nothing stays the same." Sometimes it was her entire arm or part of the arm that hurt. Like on top of her forearm. The patient thought she was doing good and then it would come back. When she moved her arm upward, she felt it. The patient said she could deal with the arm pain. It was the knotting up pains that were the worst. The patient tried calling an institute (name withheld) because it happened while eating dinner the other night. The institute (name withheld) "nurse was useless." The pain was across her sacroiliac area. The patient had been "living on Advil and ibuprofen for her back pain." The patient had been taking them together. The patient worked nights, and she was planning on going to work the night before the report, but she had to text her boss and tell her she could not come in. The patient was in good health; had perfect blood pressure and her sugar was normal. The patient was not diabetic. The patient's labs were always normal. The patient was really dreading that second shot. "The flu shot kicked her butt for a couple of days, but this was way worse." The patient started reading up on the COVID vaccine, and it said usually younger people had severe side effects. That old people have less of a response. The patient did not know why she was experiencing such side effects. At the time of the report, it was day 7 or 8, and she was still feeling bad.  The patient did not receive any other vaccine within 4 weeks prior to the COVID vaccine. Prior to the vaccination, the patient was not diagnosed with COVID-19. Since the vaccination, the patient had not been tested for COVID-19.