I had brown discharge 2 weeks after my last period, and now (lasted 2 days), and now 3 days before my next, I noticed light red blood...What could be?

More details needed. Significance of such unusual vaginal bleeding depends on age, examination findings and other variables. Consulting your doctor with answers to these additional questions is appropriate.
Could be infection. This could be due to a vaginal infection or it could be normal after a menstrual cycle where you did not completely shed the lining of your uterus. In which case it could represent old blood. Your physician should be able to do a simple exam and obtain a culture in their office to evaluate for possible infection.