Hi, So I Am 19 Years Old (female) And Thursday

Hi,
So I am 19 years old (female) and Thursday I had sex for the first time (u protected) and and now (saturday) I am noticing a yellowish vaginal discharge since Friday. It had like a fishy odour and its embarrassing. I am worried that it might be an infection. Thursday night my lower tummy was hurting a lot (I dont know if it would help to figure our what's going on...) should I be worried or this is normal? I am on a vacation and I want to know if I should go buy medecine or anything to stop the infection if it is an infection....