tiny blister appeared, should i be worried?

as i was peeing when i woke up in the morning, i saw a small blister (idk if u call blister) on this part of my penis. it doesn’t hurt tho or itchy. it also doesn’t hurt when i pee or masturbate. but i had an unprotected anal sex last month, pls what is it?

This is rather undefinitive as to what is actually going on it may be something developing or a simple skin imperfection. All you can do is see whether it develops any further - if you have concerns regarding the unprotected only thing you can do is go get tested