Have you seen a neuromuscular specialist? Have you been evaluated for multiple sclerosis?

Flu like feelings, weakness can be signs of diabetes. So I'd get that checked too. Also flu like symptoms can be signs of infection.
A festering kidney or bladder infection can cause systemic signs like you describe.

It sounds like you need to see a doctor ASAP to get further evaluation. People can have more than one thing going on.
Once they get a diagnosis of ANYTHING, they tend to blame further symptoms on that, and fail to get evaluated for new symptoms.