My boyfriend and I have been having sex every day, twice a day for a little less than a month now. Recently we have noticed that there was a tiny scab on the shaft his penis, just under the head. We figured it was nothing, we had sex and the scab part fell off and revealed a small red spot where the scab was. After a couple days the area hardened into a bump on his penis. What is it? Is it STI related? Or just because we have been having sex so much?