Blister looking things under foreskin

Alrighty, just wanted to ask some questions, earlier today I found some blister looking things under my foreskin and I was wondering if anyone else has experienced this? I have only had protected sex before and was curious if it is somehow a STI/STD or if it is just irritation. If need more info just ask, I am not too sure what to all say or if this is the right place to post.