I Feel As Though I Thought I Had A Yeast

I feel as though I thought I had a yeast infection. So a few weeks ago I took monistat one. But my husband is in the military and came home, therefore I had sex. I think I have a YI because I was put on amoxocillin for dental reasons, this was like 2 months ago. So, yesterday I got monistat 3 cause I am still experience issues. My issues are thick white discharge nonstop and pain sometimes. Anyway, the monistat doesn't seem to stay and now I seem to have my period a week early!! Please help I am scared.