I'm having abdominal pain and I'm not pregnant. I notice that I'm spotting and it's not red but brown what do I need to do?

Needs Exam. Spotting and pain with a confirmed negative pregnancy test can stems from various pathologies surrounding the cervix and uterine walls either due to irritation, infection, hormonal dystegulation. You will need to followup with your ob/gyn or primary doc. For exam.
See your doctor. Your pain could have many causes, but you need to be examined to sort them out. With the spotting, you could have a pelvic infection. See your gynecologist or your family doctor.