worried that she was having a heart attack; terrible pains in her upper back, down her chest and into her arms; terrible pains in her upper back, down her chest and into her arms; terrible pains in her upper back, down her chest and into her arms; very fatigued for several days afterwards, like 5 to 6 days; might of been having a reaction where her bone marrow flared up in response to activating the immune system after the vaccine; This is a spontaneous report received via agency from a contactable consumer, the patient. A female patient of an unspecified age received the second dose of BNT162B2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE; Lot Number: UNKNOWN) via an unspecified route of administration on 24Mar2021 as a single dose for COVID-19 immunisation. Medical history included ovarian cancer from 2009 to an unknown date (12 years ago), and ongoing inflammatory breast cancer in Mar2021 (diagnosed after the first dose of BNT162B2). Concomitant medications included ibuprofen for an unspecified indication, start and stop date were not reported.  The patient previously received the first dose of BNT162b2 around 04Mar2021 (Lot Number:) for COVID-19 immunisation and experienced chills, and was diagnosed with inflammatory breast cancer. The patient experienced worried that she was having a heart attack, terrible pains in her upper back, down her chest and into her arms, very fatigued for several days afterwards, like 5 to 6 days, might of been having a reaction where her bone marrow flared up in response to activating the immune system after the vaccine.  Clinical course: The patient was diagnosed with inflammatory breast cancer in Mar2021 after the first dose of BNT162B2 (captured in Pfizer case #2021478054). The patient has had all the tests and the mammogram did show that she had a couple of calcifications but it mainly showed all of the fluid that has went into her breast and she could of had a mammogram beforehand and the calcifications may not of shown. They have been doing PET scans and there has not been any spread. The patient took ibuprofen after the second dose of BNT162B2 vaccination. The next day after her second dose she had terrible pains in her upper back, down her chest and into her arms. She also was very fatigued for several days afterwards, like 5 to 6 days. Her pain was pretty significant. It was even affecting her upper body and down her chest so she was worried that she was having a heart attack, but that subsided after a day or a couple of days. When it kind of went away, she was very fatigued. She told her doctor about all the pain that she had after the second dose. The doctor indicated that she might have been having a reaction where her bone marrow flared up in response to activating the immune system after the vaccine. The outcome of the events, experienced worried that she was having a heart attack, terrible pains in her upper back, down her chest and into her arms, very fatigued for several days afterwards, like 5 to 6 days, might of been having a reaction where her bone marrow flared up in response to activating the immune system after the vaccine, was unknown.   Information on the lot/batch number has been requested.