Her heart rate in the vaccinated arm had a mark for arrhythmia; inflammation in the vaccinated arm; some aching in the arm but I thought perhaps the stiffness is going to be, the onset of stiffness; If I put my arm bended towards my chest that's when I would feel sort of a pop or some type of spasm and I drop my arm just like shake it off that would stop the static; Some aching in the arm; She thought she felt muscle spasms in the vaccinated arm; This is a spontaneous report from a contactable consumer (patient). A 34-year-old female patient received the first dose of  BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, Batch/Lot Number: EN6208), via an unspecified route of administration on an unspecified date (at the age of 34-years-old) as a single dose for COVID-19 immunisation. Medical history included endometriosis from an unknown date and unknown if ongoing. The patient's concomitant medications were not reported. The patient received the 1st dose of the Pfizer COVID vaccine on Tuesday (unspecified date). She thought she felt muscle spasms in the vaccinated arm, it felt like it was matching her heart rate. Her heart rate in the vaccinated arm had a mark for arrhythmia. She spoke to a family member who is a medical student, he thought it was caused by pressure on the vessel or pressure on the area. She reported having a rare form of microscopic endometriosis. She also read in a magazine that there were 36 cases of severe reactions after receiving the COVID vaccine. Not sure if it was the Pfizer COVID vaccine, but in one case, a female had heavy vaginal bleeding and her obstetrician found that she had 0 platelets although the week before her platelet count was normal. On 19Mar2021, when probed for the side effects experienced, consumer stated, "Yesterday there was some aching in the arm but I thought perhaps the stiffness is going to be, the onset of stiffness is going to start but it didn't start as stiffness it just started progression to muscle out what I thought, muscle spasm. If I put my arm bended towards my chest that's when I would feel sort of a pop or some type of spasm and I drop my arm just like shake it off that would stop the static. When I work at my desk I keep my arm folded and today this morning is when I started to feel that the spasm in my fore arm sort of matched my heart rate a little bit and I thought do I feel my heart rate in my arm I thought that was impossible but apparently you can. I have a blood pressure check machine just to make sure I don't have high blood pressure which I have never had but I just in case you just want to check your 'vital signs'. I put that on, it also checks 'report' and your heart rate. I put it on my right arm which was the non-vaccinated arm because I didn't want to irritate inflammation in the vaccinated arm. When I put it my right arm my 'signs' they were perfectly fine and it was 118 over 66 and pulse rate 85 but I thought, you know I really need to check the arm that I felt the, that was vaccinated but I actually felt the heart beating through the arm 'is due to' muscle spasm so I put the device on that arm that was vaccinated, my left arm and when the results stopped it was completed, it was 107 over 68, 81 Pulse but then it had the notation that I had arrhythmia, I thought that here must be the heart , I don't know if it was skipping and so I thought it is a perhaps a blood clot matter but I keeping think what Pfizer had blood clot side effects so that's where I started to check and when I started to check on maybe compression or maybe inflammation I didn't want to assume blood clot so I checked for inflammation and compression. My sister's husband is a doctor, he said it sounds like Thoracic outlet syndrome and that compression but then there is like the 'veins' one which is the blood clot, then I thought man that does sound like what I have but the fact that it was involved with blood clot but let me check to see if Pfizer did have a blood issue or a blood clot matter, that's when I thought those rare side effects. I have Endometriosis (History) but I have rare type of Endometriosis that's called microscopic (not spelled) and so it travels throughout head to toe of my body and always triggers some sort of inflammatory problem that mimic other type of condition, either trigger finger arthritis and then I don't get also sensation and then it's ruled out and then I don't have it back but it mimics something that's different and that's what I am little concerned because if the vaccine attacks right there." For treatment, consumer stated, "I did immediately because I have heavy blood flow with Endometriosis, it's little bit frightening that the vaccine could be taking out my platelets and if I start bleeding I may just end up hemorrhaging and I went to online because the fastest thing to do on weekend, it's doing online when I did quick diagnostic to do the complete blood count to check my platelet numbers are okay so I just ran to the store that has a blood diagnostic and they were closing so I explained to them my concern about maybe having ITP and they could be attacking my platelets and if they could just you know stumbles it  later and draw the blood they did so I am waiting that may take a day to receive the results." The patient underwent lab tests and procedures which included blood pressure measurement: 118 over 66 and 107 over 68, full blood count: result unknown, heart rate: 85 and 81, SARS-COV-2 test: unknown result and weight: i think i am now 190 on unspecified dates. The outcome of the events was unknown.