I am not sure about your discomfort in your arm. However, you may have TMJ issue or perhaps you are clenching/grinding your teeth at night when you are asleep.
I did some searching regarding your problem. It seems to be a common,problem for people.
Here is a web site I found that tells you what TMJ is
You may want to speak to the dentist you are seeing and explain all of what is going on. They should be able to advise you and to help treat your issues relating to your teeth.