red bump on his penis?

my hub and i were having intercourse. after he finished, we both got up to wipe, he showed and told me he has a red bump on his penis head. he said it hurts and he just got it right after having sex w me. what could it be? i was worried, went to do research, he got mad and told me to stop doing research, its nothing. he also said it burns when he pee while having sex. could he be having some kind of sexual diseases? how would i know if i have it too if it is disease hes having?