TSH is thyroid stimulating hormone so the higher the number, the worse your thyroid is responding. Technically the "normal" range goes all the way up to 4.20, but the therapeutic range for thyroxine supplementation is much lower. I think they try to keep it no higher than 1.5.
So that alone would be a good explanation for exhaustion, but also my vitamin D has gone splat again. It's currently around 67 nmol/L. Since I am on a medication which destroys vitamin D, I take a supplement all the time. But when I was having tachycardia, I decreased the dose. Apparently this was a big mistake.
In unrelated news, I have a new phone and am struggling horribly with the official lj client for Android. What do you people use?