Regular 28days period cycle 7 days bleeding but since 2 months 3days heardly brown spots and 5 days bleeding(last 2 days again brown spots)its normal?

Probably normal. : If you are using adequate birth control it is very unlikely that you have a serious pathology ... If your periods get lighter get a thyroid function test with your doctor.

Periods: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections ; hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate the menstrual cycle. Schedule a visit.