What Causes Abnormal, Heavy Bleeding In Between A Menstrual Cycle?

Experiencing abnormal, heavy bleeding. I m in-between menstrual cycles, and normally have a med-light period that comes regular each month. Ive never bled like this before, - I m soaking through tampons, through my clothes to where it is dripping on the floor. Ive been bleeding like this for almost 2 week now. Should I go to the hospital or wait for a gyno apt? I was due for a depo shot nearly 2 months ago (may 1-14th timeframe) and couldn t afford it, so I let it lapse (Haven t gotten another one since). Shortly after I missed getting the shot i had my period w/ average (not light not heavy) bleeding for about a week. To be expected. Well, about 2 weeks ago I had some pains in my R hip area that I thought was exercise-induced but haven t gone away and I haven t exercised since then.