I haven't had a period in 4 months and all of a sudden i keep bleeding on and off i keep bleeding on and off and get cramps like my period is coming but doesn't

Normally, : Normally, the lining of your uterus is shed each month. When you don’t have a period, the lining of your uterus continues to grow. When it gets too thick, it begins to bleed randomly. If this continues, it can turn into very heavy bleeding what can be serious. I recommend that you see your local ob/gyn as soon as possible. They will know what to do to get you back on track.