I'm Having An Issue With Bleeding And Do Not Know

I'm having an issue with bleeding and do not know if a waiting till Monday to see a dr or going to the ER. The bleeding at first was light. I thought nothing maybe I was spotting last month I spotted for a day around the same time. This was 15 days after the first day of my last period right after my ovulation window. It got heavier started brown and turned bright red. It's a very thin consistency and I've been leaking at night because it's so thin. It's heavy to points were it feels like it's dripping for an hr. And doesn't seen as bad when I'm standing. This has been going on for 4 days now. I've been getting light headed. And I can not remeber anything like this happening before. I have not been on birth control for the last 2 and a half yrs. I've read things online trying to ease my mind nothing sounds like what I'm experiencing.