What Causes Inconsistencies In Periods?

Hi, I have been feeling 'not right' for the past couple of weeks. Nauseated, light headed, and a weird feeling in my stomach. As soon as I press on my stomach the nausea seems to get worst. I have had a baby a year ago, and was diagnosed with post partÃ??m depression. Though I am feeling great now, I am still taking the medications. My last two periods were quite different from usual. It was really heavy with alot of bigger sized blood cloths. (about the size of a golf ball) and it was on going for approximately an hour, I couldn't get up or it was just pouring out. Yesterday after my husband and I had sex, I went to clean myself and Noticed that my discharge was greyish. It was lumpy in texture and just weird looking. No fowl odor, no odor at all. I am a bit nervous and I am thinking this may be why I haven't been feeling 100% for the last few weeks. thank you