Don't just 'check' the basic T-3 and T-4 levels, there are free T3 and 4's and also...more importantly the immune/autoimmune T3 and T4's. The latter is what should be checked out thoroughly! and monitored often. When the thyroid goes whacky, other endocrine glands help take up some of the slack, but they too can have too much asked of them.
Check out this site: http://www.endocrineweb.com/
It will tell you more than enough to deal with things, I hope. Basic info will help you make better informed decisions...
All the best! - j