Diagnosed 8 years ago with underactive thyroid recently had blood test take 100mcg. but always feel unwell and tired hair falling out why?

I'm sure that your: Tsh level is closely monitored and medicine dose adjusted by your dr . Sometimes the dr makes the adjustment of the meds not only based on the TSH but also on your symptoms. Perhaps, there are other autoimmune and psychological issues- anxiety, depression, insomnia etc- that contribute to your problem. Discuss these in detail with your pcp.Take care!