Has anyone else missed a period, had two weeks of light-dark brown discharge and some fresh blood, then a 12+ day period?

I haven’t been sexually active in two years. Masturbation isn’t rough. I’m 20. Physically healthy. I have a good diet. My periods are usually medium-heavy over four or five days, but this one has been light to medium over 12 days.

My uncle is an obgyn, so I plan on asking him before I make an appointment anywhere because google hasn’t provided any answers so I thought I’d check here first.