Same thing happened to me. Started on selenium and coconut oil and am now hyper... my TSH went down to 0.015 in 2 months. At least its a good sign the ol' thyroid still works. I've cut down on meds & selenium till my body calms down. The hyper symptoms are not any more fun than the hypo.
The standard selenium treatment for thyroid is to start with 200mcg daily for 2 weeks, then drop down to 100mcg daily after that as a maintenance dose. Notice the measurement is micrograms not milligrams.