Hi there,
I have lupus and fibro. Gosh, all of your symptoms could be lupus, fibro, or both.... I have a heck of a time knowing which one is flaring for me too.
The only way I know what end is up, is when I get my blood work done. If all the blood work comes back normal, then I know it's my Fibro flaring. There won't be anything wrong with my CBC, liver enzymes, urine, sed rate, etc.
What stands out for me when I read over your symptoms is the muscle pain you have. That is definitely fibro. In lupus, it's 100% in our joints. The bone. Lupus arthritis is common. But in Fibro, it's the muscle, ligament and tendons that have the pain. No joint or bone involvement.
I had a recent hospital stay two weeks ago. I had a hysterectomy and was in the hospital for 4 days. I had horrible dizziness, coordination problems, leg weakness, etc. I was in a horrible fibro flare. What is also standing out for me in your symptom list is the frequent urination. Fibro will cause irritable bladder syndrome. It'll feel like a bladder infection for some people, and most commonly, the need to urinate frequently becomes a problem!! I get that too.
I'd say, if your blood work came back normal (with the exception of the borderline + ANA), it's probably your Fibro. A large percentage of the general population will have a borderline + ANA and never have any other symptoms that might be lupus or any other autoimmune disorder. If you had no other positive lupus or RA blood work come back, rest assured, it's your Fibro.
Hope this helps,
Ginny