His balls are sore?!?

So my boyfriend texted me saying his balls are sore , and he is in a lot of pain?! We aren't sure what is wrong but he said he had dealt with it before in the past but it normally goes away , he's super sensitive in his penis and i noticed his penis smelt bad and we always use condoms. So should I be worried and get an std test? we read online that if he cums into the condom and the sperm goes back in side it can cause infections and stuff, he said it feelings like he's been punched in the balls. I'm concerned :/ and a little worried about getting an STD