Maxbert
what you are describing sounds like some of the symptoms of an over-active thyroid gland, aka "hyperthyrotoxicosis".
The Thyroid controls your metabolic rate.
If you are (a) skinny, eat anything and never put on weight (b) have tremors in the hands - and generally 'the shakes' (c) are nervous & on edge (d) have disrupted sleep patterns (e) suffer pain/aches in the eyes (f) have slighly protruding eyeballs ... and a whole bunch of other stuff
Then there is a good chance that's what you've got. AND your G.P. won't recognise it .
Suggest you ask for a blood test for that condition.
p.s. You doctor will want to put you on tranquilisers because he WON'T recognies the symptoms, or.. if he does, if you have epithelial ((I think that's the term)) extension ((where the thyroid is not only overactive, it grows as a 2-3 cell thick layer in the tissues of the neck)) he won't be able to feel its presence and will dismiss your concerns. Then you will have to get another GP
Best of luck
p.p.s. yep been there done that, got chucked out of that doctor's patient list, but at least I'm not dead. Never trust the quacks