I Have Fsh Dystrophy But Instead Of Gaining Weight I

I have fsh dystrophy but instead of gaining weight I have gone from all most 300lbs down to just barely 106lbs & noone can figure out why. I changed to a somewhat better diet at work (3rd shift) and it was gradual at first, normal but then it wouldn't slow down or stop. Any thoughts or ideas? I'm. Really getting desperate. Any held appreciated..