Why have I had so much discharge lately?

I am 17. I have been having a lot of vaginal discharge lately. I am not a virgin, but I stopped having sex about two weeks ago, and since then I have been having a lot of discharge. I have so much that it seems like I have peed my pants. I have to wear pads to keep it from getting through my pants. I have been checked for STDs and had a pap smear and I am clean. I know I don't have a urinary infection, because I have had them before and they have never been like this before. It also does not have an odor, itch, or burn. So could someone please help me with this? Thanks.