Rash question

I have a question in regards to the errin tablets. I have been taking them for about 4 months. The last couple of months, if my boyfriend and I have sex while I am on my period, he gotten a rash-sort of like pimples on his lower stomach and surrounding area. Could this be a side effect from the Errin tablets? We have never had this problem in the past before I started taking the pill. This will last about 3-4 days, but we can't figure out why this is happening. I am assuming something to do with the pills. And is there anything to help this. He has been putting a medicated cream on the area that gets infected from Walgreens. We are looking for any other solutions or answers to why this is happening.