Her right arm is also hurting. Her right arm does not hurt all of the time, just sometimes.; but Friday morning she experienced right breast pain/Three to four days ago, her right breast began hurting; experienced right breast pain and her right breast feels "heavier" and "tighter" than her left and it feels like "lumps".; experienced right breast pain and her right breast feels "heavier" and "tighter" than her left and it feels like "lumps".; This is a spontaneous report received from a contactable consumer or other non-health care professional. This female consumer (patient) reported that a 43-years-old female patient received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE, solution for injection, Batch/Lot Number: EWO187), via an unspecified route of administration, administered in right arm (at the age of 43-years-old) on 28May2021 14:30 as 2nd dose, single dose for covid-19 immunisation. The patient's medical history was not reported. Her mother has breast cancer. The patient did not have history of previous immunization with the Pfizer vaccine considered as suspect. No additional Vaccines Administered on Same Date of the Pfizer Suspect and no prior Vaccinations (within 4 weeks). The patient's concomitant medications were not reported. Historical vaccine included first dose of BNT162B2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, Formulation: unknown, Lot number and Expiration date: EWO173), via an unspecified route of administration in arm right on 05May2021 14:30 as 1st dose, single dose for COVID-19 immunisation and had no reaction on previous exposure to vaccine. The patient reported that within the last 2 weeks, she began experiencing right arm pain and right breast pain. She reports that up until last Friday morning (11Jun2021), it was tolerable, but Friday morning she experienced right breast pain and her right breast feels "heavier" and "tighter" than her left and it feels like "lumps". Her right breast feels heavier than the left one. She says that she does not take medication of any kind and that the covid-19 vaccine is the first thing she's had in 10-12 years. She states that she will call her doctor but may not take anything if they prescribe it and will just wait and see if this will go away on its own. She also reported being able to see the difference in size. She reports she read online that these side effects are normal and is calling today to ask if these symptoms have been reported. Her right arm does not hurt all the time, just sometimes. She is asking if she should be concerned and see a doctor. Before she had her period, she felt heaviness in her right breast. It was not something she really noticed; it is there every month. But on Friday, 11Jun2021, she really noticed it. Her right breast felt heavier. It felt different while she was walking, and she was feeling heaviness on her right breast. The next day her right arm was not hurting, but today her arm is hurting hard. She has been trying to drink a lot of water and juice, hoping it will get better. She does not take medications. This is the first time she has taken any medication in 20 years. She states yesterday was a little better, but not much of a difference. There was a very little difference between today and yesterday. Her breast and arm hurt worse whenever she is walking. She is fine, she knows this is because of the vaccine. She is asking should she be concerned. She did not want it initially. Everyone was taking it. She was not sure if she was doing the right thing by not taking it. She works. She felt pressure from society and her family to take the covid vaccine. It took her a couple of weeks to decide if she should get it or not. She does not take medications. She was not sure if she should get the covid vaccine or not, and it was bothering her. The patient stated that she does not have any medical conditions to include. She does not have very good stamina. She gets tired easy. She is on a diet to maintain that. She is not a weak person; she goes on hikes. She must work on her balance. The patient was not recovered from the events.