Late then mulitple periods just diagnosed hypothyroid

recently had a late period (42 days) and had gone to the ob. diagnosed as hypothyroid. since the late period I have now had 2 periods within 3 weeks. first one was 5 days and very light. second one now at 10 days. is this just my hormones still being out of whack from the hypothyroid and now the medication. I have only been taking the medicine 3 1/2 weeks. OB found nothing else abnormal on the tests - not pregnant, no other levels out of whack.