Possible STI?

I was having sex with my now ex boyfriend and we didn’t use a condom. He said he was clean and he had been recently tested, but ever since then my vag has been itchy. it’s not constantly itchy but enough to the point where I’m concerned. Could it be an STI or STD? Where do I go to get checked? I had my gyno appointment a few weeks ago and I was clean then but if I go to a walk in clinic can they test me?