Please contact a chiropractor and have some X-rays of your back and get some treatment before this develops into something more serious like arthritis or a herniated disc.
If your job requires you to stand for long periods of time you might consider asking your bosses for a cashiers mat to stand on.
Please return to the doctor who treated your elbow and have an MRI done and possibly consult with a neurologist.
Also, it could be that you broke your collar bone (clavicle in doctor talk) years ago and it did not heal properly.
Barring those two issues, it is a biomechanical problem (how your joints and muscles work together) from working one side harder than the other, postural issues due to ergonomics (how your desk and computer is set up) of your work place or an injury from years ago.
I recommend a proper examination by a chiropractor to diagnose what is going on and correct it. Over the years this imbalance could lead to arthritis in that shoulder.
Many people develop a slight tremor as they age and we call that "senile tremor" (which DOES NOT mean your mother is getting dementia), but it does mean the part of the brain that controls her motion is not working as good as it used to. A more serious condition could be something called "Parkinson's". It is a progressive condition and should be taken seriously.
There are other causes, too numerous to list, but that is why you need to consult a professional.
Please consult a neurologist about this, soon.
My father is suffering from severe back pain. Can it be treated with manual adjustment of the spine?
However, there are several other factors you will have to take into account. Has your auto insurance authorized care? They might not after waiting so long. So, you might have to use your health insurance to assist with paying for insurance.