Help! Unexplained pain during sex??

Nancy
Hi! So I've started hooking up with this guy, the first two nights were great and then the third day it hurt LOADS and we haven't been able to have sex since and it's been 3 days since and still too painful. The thing is I leave in a few days so time really is of the essence :-( I haven't had much action before this so initially when I was a bit sore I put it down to that, but now it's just getting ridiculous! 
I've thought of a few potential causes - I actually had to have the morning after pill because the condom broke on the second night and the first time it hurt was the first time after that. I've also been on antibiotics for a while for an ear infection but I was on them before and it didn't hurt. I really don't think it's an STD, I've only had sex with one other guy and he was a virgin too and the guy I'm with now got tested recently. The only other thing I can think that it may be is a weird tropical disease as I've been abroad in remote places for a while now but why would that come on so suddenly? 
Anyway, any advice?? We've tried different positions and going slowly and all but to no avail. I don't feel comfortable going to a doctor here in this country about it. I just wanna get laid again before I leave!