What Causes Abnormal Bleeding During Periods?

I had a m/c 2 years ago and my cycles are just getting back to normal now. My pms has declined greatly. I have been taking Chasteberry for a few months to regulate me. However the only problem I have is that my period is still weird. I bleed light to medium for 3 or 4 days and then it stops. I will spot here and there for 3 or 4 days and then it'll start again heavier than before with clots. Nothing too big. Dime sized clots. But why do I have a break in the middle? I have seen my gyno a few months ago and he was satisfied with my "regular" cycles.