The first issue will be whether failing to diagnose you with hypothyroidism was "reasonable" or not, since even if it was in error, it may have been a reasonable diagnosis. The law accepts that doctors are not perfect: if the diagnosis you previously received was reasonable under the circumstances and given the symptoms, the doctors would not be liable.The second issue is what damages you can prove--you'd have to prove concrete legally cognizable losses from a misdiagnosis. Quality of life impairment is something you can in theory collect for, but it can be very difficult to prove to a sufficient level as to get worthwhile compensation.You should consult with a medical malpractice attorney about the situation in detail, but you need to be prepared that his/her advice may be that this could be a very difficult case to bring and win.