Welcome to Neuro Talk. Sorry for what brought you here however. Your GP was correct this most likely out of his ballpark. However, didn't he make any kind of suggestion on what you are to do? No direction or opinion at all?
If so, get another GP Maybe look into what a Physiatrist is. This is not for mental conditions, rather they take a look at the whole body and what is going on. Most doctors, make referrals to other specialty fields of medicine when they are stumped. A good neurologist is also a start. You may need this GP for the referral to get into see one. That is why I am a bit surprised you doctor gave you no direction, nor a referral to any other field of medicine.
Your symptoms sound neurological in how you describe it. That field is very complex and you should see the very best doctor you can find. Sometimes it is very difficult to DX and people on NT have been through what you are experiencing. Not knowing where to turn. Hopefully you will get some good responses on where to start first. It is the question of finding the best help for a DX. All my best to you. ginnie