My latest flare up has lasted two years now. It is by far the worst I have ever been and I have dealt with these same symptoms along with other things almost on a daily basis. I was just recently diagnosed with fibromyalgia and my primary and I chose to try Cymbalta first to see if it could help since I have GAD and it helps with anxiety. Stress is my ultimate trigger whether that stress is physical or emotional doesn’t matter my body doesn’t seem to know the difference. It’s like the egg and the chicken which one came first my anxiety or my pain. I am finding great relief with the Cymbalta not only with the severity of pain but with my anxiety as well including the shakiness, back trembling (muscle trembling), tightness, shortness of breath, and numbness and tingling. It does not prevent my pain but provides great relief from the intensity of it.

Have you been tested/treated for an infection? I wonder if it is related to an infection, or a fibro flare up because of one.
I am taking Lyrica, something I fought taking for years, until the muscle tremors got so bad, I could barely function, but am no longer having tremors.

I have that sometimes too

This happens to me as well, The first doctor I went to laughed at me! So I just kept going to different ones until someone listened. The rheumatologist I saw said that it is from the fibromyalgia, I'm not sure how to help manage it though :(

Gastro or neurologist doctor - not always fibro