Please guide me!!! I've searched the whole internet!!!

First off let me start by saying we've been trying to conceive since December. I've had normal periods until February. Sorta. My periods went from being 7 days to 5 and start and stop. No, I'm not pregnant. Since February the week after my fertile week I had a week of dark brown discharge until the day of AF. Which again was spotty but continuous. Now here I am in March, again 6DPO and am having brown discharge again. This one had brown all over the tampon and at the top was some blood. I have 7 days before my period. This normally doesn't happen. Why has this been happening... Can anyone tell me what this is???? I have no STDs no diseases or anything. I'm desperate.... Any ideas...