Penis red lump ? Or rash?

So last night while having oral sex with my boyfriend I notice he have a red lump on his penis, and I’m kind of worrying I don’t know what this can be, also he have a lot of little of blisters on one side of his cheeks inside

Should I worry about him?

I was virgin when I started dating him and I made him get tested for stds and he came out clean, is been a year already.

Can that still be a std?