4th day after second pfizer vaccine, and armpit still feels sore to touch in one area, like its bruised almost, im getting worried, shouldnt it be gone by now?

Armpit discomfort is not uncommon with the vaccine jab and most side effects have departed by day 3, but there are a few folks who note a bit lengthier persistence. (Everyone is different.) If you believe that your armpit is worsening, phone your doctor and discuss the next plans, but most likely, this will continue to improve.

Not unusual. Just wait it out. Good Luck