I had sex with someone of unknown hiv status i did use a condom and she was on her period but when i pulled out and took condom off to wipe myself i noticed blood on my penis did the blood get inside condom? am i at risk of hiv exposure? please help?

Should be ok: Blood on penis probably resulted when you withdrew from her. Risk of HIV using condom is low even if she is positive which again the likelihood is low.

Possibly: If she is hiv positive and her blood entered your bloodstream through some open sore, you are at significant risk. It would be helpful if you know her status. I recommend that you get fully tested by your MD or through a clinic.