Constant bleeding for last 21 days.

I'm bleeding constantly for past 21 days starting 6th March. Bleeding is little, mostly while I pee or during intercourse. Before this too I didn't have normal periods, there was a Spotting for 3 days starting 6th of Feb, and a prolonged period before that from 23-29 Jan. This has never happened to me before. Usually my periods come between 25-30 days interval and last for 3 days normally and a bit of Spotting for 2-3 days. I've taken two emergency contraceptive pills in the month of Jan. At first, I thought this is a side effect of taking two pills in a month, but now I'm scared since it is not stopping. I've taken pregnancy test too, twice, which came out to be negative both the times. My age is 25. Also, my vagina swells almost every time during intercourse, and I've consulted doctors regarding this, but they say it's nothing just an yeast infection. Please help me out.