What do i do...what could it be...?

I have been eating lots of watermellon. and well my poop has been red. I automatically put the red with watedmelon and pushed it off. but at the time I was having diarea because im bulimic and well I abuse laxatives and purge. well I sort of just went #2 and it looked more like blood. and now im nervous. what do u think it is. and I am being serious. I am going to dr. just in case but do u have any ideas just to be prepared. im 19 year old female. please help....? thanks