I took vaccine on july 31st. Aug 7 i got my periods as per due date but flow was light and lasted only aug 8. Again aug 15 i got periods which was heavy and more cramping. Lasted for 4 days. Took preg test beta hcg was negative. Tsh is around 8.but even after period ending i have severe cramps and back pain.. It gives me a feeling i can get anytime.. This is due to vaccine or thyroid? What should i do next ?