Why Does Mucus Appear In Periods?

Hi, so I was on some antibiotics for a tooth not long ago.. ( I didnt not finish taking them all because i have a bad habit of forgetting) I though I had gotten a yeast infection from the pills. I have never gotten one before prior to this... Not even with antibiotics... Now about 3-4 weeks ago my Dr. prescribed me provera because I do not have my periods...After I finished the pills I got my period a few days after... I finished about a week and half ago... maybe 2... When I got the yeast infection (if that s what it is) I noticed little pink spots on the toilet paper... I began looking on line for what could it be... Everything lead up to pregnancy... I got a test.. Big fat negative. :( But now its as if I am on my period all over again.. But its very mucusy... Stringy and its a lot i mean a lot... what could be wrong....