I had this problem for months while traveling and I thought I was going to lose my mind over it. Be sure that your problem is actually yeast and not a bacterial infection. They are treated differently. I'd see your Gyn if you haven't yet. Maybe the over the counter meds aren't the right thing for you since they treat yeast infections, not bacterial infections.
By the way, after I was better, I panicked when I thought the whole infection was starting again. So I finally took some advice I read online and put some apple cider vinegar in a bath. It restored the Ph level and helped keep the infection away. It took about 3 days of doing that for me to notice that the uncomfortableness was completely gone.
UC for the last ten years
Current Meds: 6MP since 2006, Cortifoam
Past Meds: You name it; I've tried it. (Asacol, Colazol, Pentasa, DiPentum, Rowasa, Canasa, Cortenema, sulfasalazine)
5ASA drugs don't work for me. Canasa seems to make me worse.