Still sounds like subacute thyroiditis, currently in HYPO phase with a high probability of full recovery. TSH is improving, would recheck in 4 weeks. Behavior can be influenced by thyroid dysfunction, but with the odds favoring recovery without treatment, it is not compelling to give thyroid hormone. He may end up needing treatment and usually this is based on symptoms and duration of elevated TSH -- should recover within 3-4 months of elevation.
I know how difficult this can be. My thirteen year old was hyperthyroid for a time, and he was absolutely impossible to deal with. He not able to sleep well due to the thyroid and was very easy to anger. I feel for you. It looks as if your son was hyper and now is hypo, although his TSH is coming down some. Good luck and patience to you.
I think you should find a doctor who will look at whether or not your son is developing a case of Hashimoto's. If he is, you might want to do a battery of allergy tests like ELISA; in particular, high gluten consumption can cause the Hashimoto's autoimmune response.
I have no doubt that behavior is related to his thyroid situation.
You need a 2nd opinion from a top doctor. You could try Mary Shomon's referrals, I believe they are at thyroid.about.com.
What exactly is the anti-body test that you do for Hashimoto's?
His 5/3/06 test stated he had a TSH Receptor Ab (TRAB)of <5%, with 15% or greater meaning a positive. His Thyroid stimulating immunoglobulin was 111, with a level above 129 indicating a positive for Grave's Disease.
The antibody tests are TPO and Tg antibodies -- as he has already had normal TRAB and TSI. If the TPO and/or Tg antibodies are positive there is a higher rate of long-term HYPO after the subacute thyroiditis (which sounds like what your son had). Again, most people recover fully on their own especially if these antibodies are normal. If treatment is started and antibodies are negative, I would recommend trying to taper off treatment in 6 months to see if the thyroid recovered on its own otherwise he would be on meds for life that he may not really need.
The behavior is likely influenced by the thyroid dysfunction but for subacute thyroiditis there is no specific thyroid treatment except to wait it out and treat some of the symptoms (but not with thyroid-specific meds).