Recently I've been told I have anxiety/depression from my GP. Basically the symptoms I'll get is;

-extreme fatigue, weak legs and struggle to walk
-can't focus properly
-mild headaches occasionally 
-feeling of dread and sudden unwillingness to want to do anything
-very very tired


The worst is the fatigue, I find my self feeling so weak at times that I struggle to walk without my legs feeling like they're going to buckle under my weight.
Been to the doctors, had bloods done, and they ultimately said I'm suffering mentally.

I'm on sertraline, which to begin with, fucked me up. Been on it about 2 weeks now and It started to feel better, until the past 2 days where its all coming back. 
I'm convinced it's something other than anxiety or depression, but at the same time, of course someone with anxiety would think that lol.

Just wondering on what other people's experience has been?