Well I am only 29 years old and for about a year now I have been having severe moods before my periods and I am having prolonged periods now, It started after I had my son 5 years ago but never was consistent till about a year now. My period is starting normal even extremely heavy, then it just stops and then goes into a brown discharge nothing heavy but enough I need to wear a panty liner to prevent stain in the panty. My periods with this going on is lasting 8 days or more now. I am not on birth control I had my tubes tyed after my son. I am with the same person for 7 years now and last year when I went to the Gyno my pap came back normal. I know the brown discharge is old blood but don't understand what can be causing it, should I go to the doc or any advice helps it is very frustrating.

Even if you don't have anything significant happen (births, miscarriage, etc.) your body will still change with time.
What you're describing can be pretty common, but best go to the doctor for another check-up.