boyfriend's dick go wrong

Elizabeth Hardy
Hi, sorry for long post.
 I was on birth control  pills 2years ago and we was not using condoms just lube. Then I had break of pills and  we usually was having sex with condom and lube. 
So now I am taking birth control pills again, around 3months already, because we are traveling abroad. But we still had sex with condom. 
So yesterday we got durex lube for ourself, and we finally had sex without condom again, was nice feeling at beginning, but then suddenly I felt horrible pain in lover tummy, felt like someone would literally stab me, I asked my boyfriend to stop. After all I still had this pain like 15min, I was nearly crying how bad it was. 
I was thinking he might hit my cervix, I do not know a lot about it, just been reading some stuffs. Or maybe I was not relaxed yet, because with lube is so easy to come into me. 
Today at evening we spotted some weird rash on my boyfriends penis. Right on the head, it's not swollen, he says it's not sore, not very itchy. But it's first time I seen something like on him.
That really made me feel uncomfortable and little bit guilty. I had yeast infection before if that says anything, we used to have sex during my yeast without condom  and he was alright. 
We was using durex lube with flavour before, this time we have got natural. 
So my questions is: 
where this pain come from? 
what's wrong with his dick? 
is it possible to catch any genitail illness if I sit on public toilet in poor countries like south east Asia, I mean like Bangkok city, it's big sex industry there, ladyboys, prostitutes, stripers. I always try to avoid sit on them, but I might did once or twice..
That's probably one of my biggest fears public toilets...
THANK YOU for reading, any comments apreachate!!! 🙂