Neurological issues of shaking and tremors mostly in her leg; Intermittent tremors or involuntary muscle contractions; Pulsating heaviness in her legs; Severe diarrhea; Loss of appetite; Constipated with no normal bowel movements; Nauseated; Felt run down and fatigued; Pain on the right side of her tail bone and upper right buttocks; Pain on the right side of her tail bone and upper right buttocks; Rash on right of tailbone and upper buttocks that progressed into blistering; Tingling in her hands, low back, and tailbone area; Depression; Original rash was shingles; Herpes simplex virus could have attacked her gastrointestinal system; Mild GI symptoms; This is a spontaneous report from a contactable consumer (patient who is a registered dietician). A 42-year-old female patient received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE),  via an unspecified route of administration, on 30Mar2021 (Lot Number: ER8732) at the age of 42 years, as first dose, single, for COVID-19 immunization. The patient's medical history included herpes simplex virus (HSV) from 12 years ago (2009) and she has not had any problems with this in a very long time (her lesions would be limited to her vulva area and she has never had an outbreak on her buttocks before). There were no concomitant medications. The patient was experiencing symptoms post COVID-19 vaccine that she wanted to report. She is seeking guidance for treatment or a provider that could help. The patient received the vaccine on 30Mar2021 and then felt run down and fatigued and developed pain on the right side of her tail bone and upper right buttocks on 01Apr2021. On 01Apr2021, she had developed a rash on right of tailbone and upper buttocks that progressed into blistering (rash in that area which then blistered). The patient had tingling in her hands, low back, and tailbone area from 01Apr2021. The patient went to urgent care (physician visit) on 03Apr2021 and was prescribed acyclovir for the symptoms above. The patient saw her primary care provider for this new onset blistered rash and given her history, she was prescribed acyclovir, she took an 8 day course of that but then started to become constipated with no normal bowel movements and started feeling nauseated on 09Apr2021. The patient took that for eight days and felt not 100%; felt bad run down. She stopped Acyclovir on Monday (12Apr2021) and was off it for two days temporarily because she was experiencing nausea and mild gastrointestinal (GI) symptoms in Apr2021. For those two days off it, the patient developed severe diarrhea with a loss of appetite starting on Tuesday (13Apr2021). The patient also had neurological issues of shaking and tremors mostly in her legs and pulsating heaviness in her legs and tingling in hands on 14Apr2021; fatigued; and depression on 01Apr2021 that worsened. She saw her primary care doctor yesterday (15Apr2021) and was prescribed more acyclovir and was started back on it. The doctor told her that herpes simplex virus could have attacked her gastrointestinal system in Apr2021. She has this shaking that feels like it starts in the back of her body that has not subsided, describes the shaking as intermittent tremors or involuntary muscle contractions. Last night (15Apr2021), she also had loss of appetite and diarrhea. The patient went to the emergency room (ER) this morning (16Apr2021) because she woke up at 3:30 and experienced same tremors from night before that went away. The patient went to the ER on 16Apr2021, they did a full work up, did not find anything. The patient was given liter of fluid for shaking and had electrocardiogram (EKG), blood work and chest X-ray that came clear (16Apr2021). She had pictures of rash when first developed on 01Apr2021 and the physician stated that it looked like shingles. The ER provider said she felt like the original rash was shingles instead of herpes simplex virus based on the pictures that the patient showed her. The doctor stated that they had heard of others developing post vaccination shingles. The patient has another follow-up with her primary care physician today (16Apr2021) for further guidance after her ER visit. The patient would like to know if Pfizer has any recommendations for treatment in this situation. The patient wanted someone to shed some light on shingles and treatment; for the first dose. The patient was recovering from "Rash on right of tailbone and upper buttocks that progressed into blistering", "Tingling in her hands, low back, and tailbone area", and "Constipated with no normal bowel movements". The outcome of "Herpes simplex virus could have attacked her gastrointestinal system" and "Pulsating heaviness in her legs" was unknown. The patient had not recovered from the remaining events.  No follow-up attempts are needed. No further information is expected.