I have cyst in my ovaries so I be on my period for about 3 months.. I went off and for the second week I was off I had unprotected sex but came on two days later. He claim he did "you know what" in me but I doubt I'm pregnant.. could I be? Its been a week since we had sex so I been on for 5 days

Any time you have sex, pregnancy is possible. So yes, you could be. It's too early to test now. You'll have to wait.