painful small red spots 2 on penis and 2-3 on testicals

i'm an early 20's male (just incase it has any relevence)

there are 2 small 2-3mm red spots on my penis shaft which are not painful at all but then have 2-3 spots on my testicals which are causing a really painful stinging. the testicals are bright red from irritation aswell but that could be self inflicted. as there is also a very slight iching sensation. (but that could be unrelated)

i had unprotected sex at the weekend although i know the girl and was pretty sure she was clean, but still am wondering if i could of caught something anyway.

i remember having something like this before several years ago but as it's happened again i want to actually check what it is just incase i need to do something about it.

thanks for any help.