I was 4 days late for my period. i finally started but it's lighter than usual and it's a mixture of brown and red. what's going on?

Hormonal: Sounds like a hormonal glitch but also consider pregnancy if that's a possibility.

Difficult: To say exactly what occurred is impossible. You may just be late on your period. Check a upt if active, that may give u an answer but unlikely. If on the pill it can happen as well but the texture or brightness of the blood infrequently has clinical significance. Good luck.