Welcome to the forum!
There is a possibility that burping, gas and indigestion casing gastric reflux irritated the phrenic nerve of the diaphragm which originates from third, fourth, and fifth cervical nerve plexus. This is the motor nerve of the diaphragm but it also sends sensory fibers to the pericardium (outer lining of heart). This can cause chest pain and weakness in the arm too. As you were burping, the chances of irritating this nerve are high.
However this alone should not be taken into consideration. Other possibilities like angina, spinal nerve compression etc should also be considered.
Hope this helps. I think you should discuss these possibilities with your doctor. Please let me know if there is any thing else and do keep me posted. Take care!
You shouldn't lose strength in an arm over gas. Please go in and get your heart checked out!