What Is The Cause And Treatment For Vaginal Infection?

I had my Gaul bladder taken out about a month and a half ago. They had me on antibiotics. When I got out of the hospital I had, what I think to be a, yeast infection. I didn t treat it or anything. It went away on its own after several days. I started my period shortly after. About a week ago I was put on antibiotics again for a tooth issue. Once again I m having a yeast infection . I have been eating yogurt and using Monistat to try and clear it up. I have this really bad feeling its not a yeast infection. My vagina burns and feels raw. I m having yellow discharge with a smell to it. Not a bad smell. But, different from my normal discharge smell. I am due to start my period soon. Please help.