Chlamydia or Yeast Infection?

Around a month and a half ago I had my what I thought was my first yeast infection. A couple weeks later the symptoms returned! I bought the OTC medicine again and the symptoms disappeared. Now I the symptoms have returned. The symptoms are chunky discharge--yes i know gross, pain during , pain while peeing, burning, and just uncomfortableness along with occasional itching. Since the symptoms have returned so many times I am going to the doctor in two days to see what it is. I was thinking it could possible be Chlamydia? My boyfriend and I were broken up for a bit and he slept with a rather promiscuous girl WITHOUT a condom. Then we got back together and a couple weeks after he slept with her and started sleeping with me, I saw symptoms. Oh and a note this other girl has not had her period in quite some time, around 8 months. Could this be from possible Chlamydia symptoms in her? I hope I don't have this, but any knowledge is very helpful!