Have your doctor take a CT scan of your shoulder. You may have an impingement. It can be taken care of by laser surgery with two or three small holes made in your shoulder. My Mom had that done in her 80s and is fine.
Xrays do not show up problems with muscles, it only shows up bones.
Ultra sound or other forms of scanning can show up muscles and tendons.
Although the xray did not show up anything wrong at the time, does not mean that the fall did not damage anything. Xrays sometimes do not show up problems in a bone immediately. There is clearly some pinching on a nerve because of the feeling of the burning pain that is running down your arm. It also may be coming from the neck.
As you fell at work, I trust that you entered this into the works accident report book. If the fall was because of a wet floor or a trip hazard that you did not see you, the work place then is negligent.
Keep a record of all your symptoms, no doubt you have kept a record of when the accident happened and had witnesses. Go back to your doctor for further investigation and a referral to physiotherapy. In the UK any claims have to be commenced within 3 years of the date of the accident. The law may be different in your country.
You probably need an MRI and an EMG (nerve function test). A CT isn't the best imaging test for this (unless a specialist is adamant about it), because CTs have much worse resolution than MRIs, and involve x-ray radiation, so if you don't need a CT and an MRI would do as well or better, go for the MRI. You could have damaged the shoulder, which is now pinching the nerve, or you could have injured your neck, which could also cause nerve pinching. Getting it sorted out quickly is important. Try to find someone in physical medicine and rehabilitation--this is exactly the kind of thing they do. It's possible for severely tightened muscle "knots" to cause nerve symptoms, but you should rule out the other possibilities first.
And jemma's right--if you haven't filed this with worker's compensation (assuming you're in the US), you should. I'm pretty sure it covers accidents that weren't negligence, and it will pay for medical visits for the injury. You'll probably need physical therapy eventually, so it's good if you can get someone else to pay for things.
Thank you so much for you responses. I did file with workes comp. I will defiantly see about getting MRI's and cat scans done. I never thought of a neck injury, but it does make sense. I've been back and forth to emerges throughout the year as I have been compensating the pain in my shoulder to my back, and have had many different diagnosis for this, as well as pain medication that does not help. Thanks for your help guys, much appreciated.
Wishing you a speedy recovery.