Hi Welcome to HCM
I have gone thru you query regarding your pain in upper arm .
 Pain any where in the body  is a common feature in daily life of all of us  It is not just happening but is the outcome of our wrong food habits and faulty life style  & lack of proper exercise. 
Fried , fast foods , tea, coffee ,alcohol ,
smoking all derail equilibirium  of the three factors  - vat -(,AIR)  pitt (BILE ) & kaph (PHELGM) and  spoil the  process of  our digestion system  Imbalance of any one deralils the  system  and leads us to unwellness and causes 
constipation which causes Vat imbalance  in our system  ,besides many health problems . So let it not happen by taking balanced diet including fiber , vitamins ,minerals , 
proteins  in natural form --grean leafy veges ,fruit , ginger, garlic   milk ,cheese  .  & lot of water  ,Turmeric a level spoon in a cup of hot milk  at bed time and fenugreek powder 1 spoon with water in the morning  also help in aleviating pains  Regularity inyour life style , proper exercise   and rest  will strengthen immune systme and help you lead  trouble free life as for as your health is concerned 
Vat -Air is responsible for pains in any part of body 
Apply hot pack  to loosen muscles and improve 
stiffness.
Staying immobile for more than a day or two actually can be harmful because it can decondition the muscles . 
Once you are feeling well enough and your doctor gives permission, practice stretching exercises to both relieve  pain and improve your flexibility.
It's best to perform these exercises after warming up muscles with a warm shower, bath, or towel.
A degenerative process can cause 
radiating pain, as well as 
numbness and weakness in your shoulders, arm, and hand ,adjust your activity level to what you can comfortably handle. As you improve, gradually increase your activity level back to normal .
 Apply gel - pain reliever  
 For instant relief Take a half cup of water, pour 4 drops of 
Homeopathic Chamoilla 30 liquid  Make 3 doses of this mixture  Take 3doses / in 15 minutes gap
  Hope this helps solve your query  Take care.All the best
Don't hesitate for further query if you have any .