I want to understand what's going on with my cycle. Help.

My period is two and a half weeks Late and it's lighter and less painful than usual. It's very late. And it's too early to tell if I was just spotting today or if it actually started for real. I haven't been particularly stressed about anything. I have been sick for months and doing a bit worse recently. Maybe it's being weird because I'm feeling sick? Or maybe it's because I changed in a medication. I don't know and I want to understand.