could not walk as both knees were hurting and swelling; muscles ache; having  pain swelling in one knee and could not bend it; having  pain swelling in one knee and could not bend it; testing me for lupus, my antibodies were high,  and then it came down; having trouble with my leg/all my muscles in my legs, they ached; have arthritis in my knees/Arthritis; broke out on a rash on my ankle, and my legs; my feet started swelling; tightness in my knees and in my muscles; I was in bed for 3 weeks; used crutches, and then I was on a walker for a couple of weeks; feel like electricity, like a nerve, it does not hurts, just a weird feeling going thru my upper arms, like it goes from one side to the other; her immune system is attacking itself; This is a spontaneous report from a contactable consumer or other non hcp (patient). A 66-year-old female patient bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE, formulation: solution for injection, Batch/Lot number was not reported), via an unspecified route of administration on an unspecified date in 2021, as DOSE 2, SINGLE (at the age of 66-year-old) for COVID-19 immunisation. The patient medical history included autoimmune deficiency and concomitant medications were not reported. The first week of January on an unspecified date in Jan2021, she took the 1st dose of bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE, formulation: solution for injection, Batch/Lot number was not reported), via an unspecified route of administrationfor COVID-19 immunisation and she was fine other than a sore arm. The second dose about 2-3 weeks later in the middle of the summer, she started having trouble with her leg. On an unspecified date in 2021, the patient had tested for lupus, experienced trouble with her leg/all her muscles in her legs ached, have arthritis in her knees/Arthritis, broke out on a rash on her ankle, and her legs, her feet started swelling, tightness in her knees and in her muscles, was in bed for 3 weeks, feel like electricity, like a nerve, it does not hurts, just a weird feeling going through her upper arms, like it goes from one side to the other and immune system is attacking itself. On an unspecified date in Jul2021, the patient experienced pain swelling in one knee and could not bend it. On 14Aug2021, the patient could not walk as both knees were hurting and swelling. At end of July, she started having pain swelling in one knee and could not bend it, and then by 14Aug, she could not walk as both knees were hurting and swelling, all her muscles in her legs, they ached. She went to the emergency room on 14Aug, via ambulance because she could not walk. They told she had arthritis in her knees, and they were testing her for lupus, her antibodies were high, and then it came down. It was not just her knees, but the muscles in legs really ache. She never had this problem in her life, and it was not going away. It was like her body; her antibodies are attacking itself. Then she broke out on a rash on her ankle, and my legs, her feet started swelling, and that kind of went away, but she still has tightness in her knees and in her muscles, like she had been walking up and down toes. She was 66 years old as of June, and she had some of this before on one knee, if she would overexert, but nothing like now, where her knees feel tight, and muscles are achy as if she was walking up and down mountain. She was given prednisone, which was not doing anything, which she was still on, and they are doing blood test. they gave her knee braces, crutches, muscle relaxers. They did x-rays on an unspecified date with unknown result, her doctor gave some arthritis medicine. It was odd it does not feel normal, not like something I have ever had. It took her a month to walk, she was in bed for 3 weeks, and used crutches, and then was on a walker for a couple of weeks. Now, able to walk but knees are tight, and muscles feel achy, like walking up and down the mountain, they ache all the time, and when she goes to bed, they throb. Also, and this is odd, at night every once in a when I am in bed, I feel like electricity, like a nerve, it does not hurt, just a weird feeling going thru my upper arms, like it goes from one side to the other, not in the middle of the body, it just comes and goes. She wanted to know if you have something that helps them. She read one guy had something like a shot to help him, but his happened to him right after he got the shot. In her case this is much later, and she did not know if Pfizer found something to help these people if it is caused by the vaccination. She had an autoimmune deficiency, her sister has lupus, and she was being tested for lupus. She was used for the pain now. They did not want her to use the treadmill. Her daughter and granddaughter got Covid, they were still having taste issues, where things did not taste right to them, and memory problems, it was a nasty little disease. The outcome of the events was not resolved at the time of this report.  The lot number for the vaccine BNT162B2 was not provided and will be requested during follow up.  Follow-up attempts are completed. No further information was expected.