Help??

Okay ladies, I'm just more confused than anything. Here the dl: I had sex for the first time in 5-6 months last weekend, and before that was my period, we'll I am now back on my period, or so I think?? I am on the patch and we used a condom as well. I still have another week until my period is really supposed to come. Any ideas of what could be going on??? This is my 4th day of bleeding. Any help is greatly appreciated! Thank you!