I don't know a lot of specifics, but I know coconut oil is thought to help your thyroid. I am not sure if that is because of Iodine content, or something else.
Too much thyroid medicine would cause the same symptoms you mention, but I never think of a food as being able to cause such strong reactions in a short period of time.
It is also thought to be a more healthy form of saturated fat because of its structure.