my boyfriend has a sore on the tip of his penis

Hey everyone, I posted this

So, people kept saying "go see a dr". I've told him the day I found out (which was a week or 2 later), he said "I'll go if my penis falls off"...but now it's starting to smell. I was sitting by him and smelled something funny, instincts told me smell closer to his crotch. I did and it smelled HORRIBLE! I cannot take the smell at all. Is that even normal!? It got bigger too!