What Causes Intermittent Brown-stained Mucous Discharge?

hello, i'm 31 yo. i have an irregular period and TTC. I took serophene twice and stopped taking it last january because I want to change my OB. But before that, I took serophene on december as well as prometrium. i had an irregular period that time, very light at first so i stopped taking prometrium then i had bleeding for a day on jan 22and it stopped. I went to another OB on last week of january and I had my papsmear than at that time. I started noticng discharge since then. Right after my visit, I noticed a lot of clear discharge came out of me as if I peed. Then on february I started walking at lunch time for about 20-30mins. I noticed that I ma getting this brown mucus discharge. I had it for 3 days right after walking so I decided not to walk for a few days and it went off. I still haven’t gotten my period but again I am noticing this brown stained mucus discharge since Saturday, on and off. By the way, last Saturday, I did strawberry picking and exercised a little.

I had several negative urine test in feb and one negative blood test last Monday, march 14 if I am not mistaken. I was told to take provera but I haven’t because I want to know what’s going on with me first. I read several posts that some women got several negative tests and turned out to be pregnant. I am requesting for an ultrasound but haven’t heard from them yet. What could be happening on me??? Please advise.