I have had light brown coloured discharge for a week instead of my regular flow. 2 days of light bleeding. Negative pregnancy test. What should I do?

Nada . It's actually common to have an occasional abnormal cycle. If on ocps, your scenario is very typical. If not on any birth control, wait it out & see if your normal cycle resumes. If it doesn't, check a pregnancy test (if you're sexually active). Consider birth control if you're not planning a family, and take it from there. Overall, i wouldn't worry. You may have just not ovulated this cycle.