Brown Discharge...

Soo ive been having brown discharge since almost a week it went away for like 2 days then im back in having it again . I was suppose to start my period last week but never came.Usually i get brown discharge before a day i start my period. What is going on ? Iam irregular. Ohhh and when i had sex with my SO like 2 days ago i bled a lil i went to the bathroom and wiped and had some mix blood with the semen tought i was allready going to start my period but it never came.