Thanks for writing to the forum!
There is one possibility that you can look into. Since the pain starts on chewing/eating, there is a chance that your father could be having a TMJ disorder. This probably causes irritation of the sternocleidomastoid muscle (SCM), which in turn causes pinching of some nerve fiber over deltoid muscle. Please consult an orthopedic specialist regarding this.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
Thank you so much. We can't tell you how much we appreciate these comments. We will definitely be looking into TMJ disorders.
Dad had a heart attack Aug. 13th, 2010. Heart cath showed major blockage. Underwent triple bypass surgery. Aug. 26th, almost no arm pain now. I think it must have been angina all along.
Oh! I am so sorry! It is so difficult to reach a diagnosis on net. I wish your father a speedy recovery.
Don't worry a thing about it. He is quickly recovering. This was in God's hands all along.