This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient.  A 75 year-old female patient received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE), administered in arm left, administration date 20Mar2021 11:30 (Lot number: EN6206) at the age of 75 years as dose 2, single for covid-19 immunisation. Relevant medical history included: "Back Problems" (unspecified if ongoing), notes: for years, started at the end of her 40s, she had gone to a chiropractor and everything; "Leg cramps" (unspecified if ongoing), notes: since the 1970s; "Disc problem" (unspecified if ongoing), notes: she guessed she had a disc problem, she had a CAT scan; "breast cancer", start date: 1999 (unspecified if ongoing); "lymph nodes", start date: 1999 (unspecified if ongoing), notes: breast cancer with lymph nodes; "Thyroid disorder" (unspecified if ongoing); "breast cancer with lymph nodes removed", start date: 1999 (unspecified if ongoing), notes: removed from her right arm; "Blood pressure abnormal" (unspecified if ongoing). Concomitant medication(s) included: FISH OIL + VITAMIN D3, start date: Mar2021 (ongoing); CALTRATE [CALCIUM CARBONATE]; CENTRUM A TO ZINC; HORSE CHESTNUT [AESCULUS HIPPOCASTANUM]; CRANBERRY; SYNTHROID taken for thyroid disorder. Past drug history included: Potassium for Leg cramps; Valium for Leg cramps; Quinine for Leg cramps; Diclofenac for Back pain, notes: Diclofenac pills, 75 mg. Vaccination history included: Bnt162b2 (dose 1, lot number: EN6202, intramuscular, anatomical Location: arm left), administration date: 27Feb2021, when the patient was 75 years old, for Covid-19 immunization. The following information was reported: BACK PAIN (non-serious) with onset 21Mar2021, outcome "recovering", described as "back pain, a more immense back pain than she was used to"; FATIGUE (non-serious) with onset 21Mar2021, outcome "unknown", described as "Fatigue"; VACCINATION SITE PAIN (non-serious) with onset 20Mar2021, outcome "recovered" (2021), described as "Sore left arm"; BODY TEMPERATURE INCREASED (non-serious), outcome "unknown", described as "temperature: 99 degrees, 98 degrees, and then 97 degrees". Relevant laboratory tests and procedures are available in the appropriate section. Therapeutic measures were taken as a result of back pain. Additional information: She only had, at first, a sore left arm later in the day on 20Mar2021, approximately 4 hours after getting the COVID-19 Vaccine. The patient also took Tylenol 3 (300-30 mg) a few hours after getting the vaccine to help with the back pain which was aching really bad. Her back pain woke her up on 21Mar2021. Her back pain was much better on 22Mar2021. She always some back pain but the back pain she had after her second COVID-19 vaccine shot was really something, it was really bad, more immense than she was used to. She also felt real tired after she got her second COVID-19 Vaccine. She didn't want to do anything. She was not nauseated. When she checked her temperature, it was 99 degrees. When she checked her temperature again, her temperature went to 98 degrees and then to 97 degrees. She doesn't take pain medication for her back unless she absolutely has too. She had bought Voltaren (clarified as generic diclofenac) when she was there. She did not like to take it because she believed that the diclofenac maybe bad for her liver or kidneys. The patient also had leg cramps during the night after she got her second COVID 19 Vaccine. She has had leg cramps since the 1970s and to scratch the leg cramps from her list of COVID-19 side effects. When she gets leg cramps, she takes potassium. She had 3-4 bananas and a squirt of liquid potassium in her mouth after she had the leg cramps. Sometimes, she would take a Valium but was told not to take it with the Tylenol #3. She ended up in the hospital once with leg cramps. The hospital gave her a shot of Tylenol. She thought she had a clot in leg. The Tylenol shot was through an IV, and the Tylenol shot relaxed her. She didn't know how much Tylenol she was given, but the Tylenol helped her. She thought she did not drink enough water. Her leg cramps were so bad, it felt like her legs were tearing apart. She would take Potassium, Valium, "Highlands", bananas, and tonic water to treat her leg cramps. She has tried everything. She said that the tonic water had quinine in it. She said she thinks she just needed to drink more water. She restarted taking 1 fish oil supplement a day approximately 2 weeks before she got her second COVID-19 Vaccine. She was also taking a cranberry supplement. She believed that she had been taking the cranberry supplement for a lot longer than fish oil supplement. Concomitant medication also included unspecified blood pressure pills which she had been taking for a long time, together with Caltrate, Centrum, and horse chestnut. No additional vaccines administered on the same date as the Pfizer suspect product. The adverse events did not require a visit to the emergency room or physician office. Patient did not receive any other vaccines within 4 weeks prior to the COVID vaccine. No follow-up attempts are possible. No further information is expected.