infection? or what can it be?

I recently had unprotected sex with a new partner who is supposedly clean, question is that since then sometimes when i pee it stings, and i sense a different kind of smell, not my usual. I have brownish discharge, sometimes on the dark yellow side but i am at the end of my period as well.

I want to know if this can be an STI or is it infection symptoms. The smell isn’t bad, but it is different than usual.

I don’t know if this background info matters but i have not been sleeping enough and did consume much alcohol over the past week. Can that infere with the smell? Even so it still stings. I just need an opinion and suggestions on what to do or take for t to go away.