uric acid is normally associate with gout. Gout occurs in the small bones of the feet.
The pain while writing, does the same pain occur while working on a computer? Could be carpel tunnel in your wrist which would explain arms also... If it is carpel then the pain should be in the thumb, index finger and middle finger area of your hand. If it is the outside two fingers of your hand then it would suggest the ulnar nerve.
Considering you experience it in arm, feet, legs; I would suggest talking to your doctor and let them lead you in the right direction for testing and diagnosis.
I'm not sure what's causing the pain but I have nerve damage in my legs the doc has me on gabapentin (neurontin) I can't say that it helps a lot but it takes some of the pain away. Maybe you should consult your doc and see if it would help you. Good luck