So this is tricky. Right now, because you are dealing with treating a thyroid issue, I would NOT go ahead and self medicate with birth control pills. You need doctor supervision. As the thyroid is so involved in our hormonal production and even our cycle, adding different hormones in as well though BC pills could upset the apple cart (as it sounds like you are finding out). This doesn't mean you will never be able to take birth control pills. I will tell you though, I had a thyroid issue and a hormone imbalance. I have not taken birth control pills since that time. I also got melasma (facial discoloring) from the hormone imbalance when on BC pills and it went away when I discontinued them. I just found other ways to prevent pregnancy. You may able to find a suitable solution with your doctor. But with your thyroid issues, you are now a more complex patient that needs professional guidance related to any hormones you take. Would agree it's the pill. Or hormonal shifting.