Hi, I Am A 68year Old Woman, Who In The

Hi, I am A 68year old woman, who in the last year have lost 20 # unintentionally, totally exhausted everyday, very nervous, which is not usually me! I now weigh 89 # and am afraid if they can't figure out why, I am going to just disappear.... Sometimes I lose awareness of my surroundings, even very familiar places. They have tested me for many things, but my neighbor just talked to me and told me she went the same thing and it was her thyroid. Is that someone that is usually checked in A blood work up? He has never mentioned it to me, maybe I should ask him for it? At my wits end, my life is very sad right now, no energy!!