Hi, thank you for all the answers, I read all of them.

I decided in the end to go to mass (I sat in the back) and even though it was crowded, I didn’t get the weird stares I expected to. I don’t believe that my rash was infectious, but even so, I did not shake anyone’s hand during the sign of peace as to make sure that I did not spread it.
Thanks so much for answering everyone, I really appreciate it.