What Causes Vaginal Discharge With Abdominal Discomfort?

I am currently on LoEstrin 24... since about March or April. I was also told I had bacterial vaginosis and treated. I was retested and everything was fine. I skipped my sugar pills in July and went three months without getting a period (despite taking the sugar pills the other two months)... although I did have some brown stringy discharge a few times when I wiped. Last month my period came a few days early... and was extremely red and fresh... but was not enough for a tampon. I developed a sinus infection and was put on Amoxicillin which I did not finish in its entirety. I had unprotected sex about a week and a half later on October 11th (still on birth control). My sinus infection was back so 3 days later I went to my regular doctor who once again prescribed Amoxicillin. He aslo did a blood pregnancy test given my skipped periods. I developed a yeast infection from the antibiotics so my doctor called in Flucanzole. I should have got my period on the 27th but it still has not come. A few days before that I wiped a few times and there was again brown stringy discharge. I'm confused as to what might be going on. I've been constipated a lot lately and having some lower abdominal discomfort... also I don't find myself wanting to eat a lot... and get full very fast. Sometimes I also get light headed.