Shoulder blade pain, arm pain and weakness

[amauzey]

I have been experiencing some strange symptoms for me.  I am a 33 year old female. I am active, I usually run between 4 to 6 miles four times a week.  I also do strength training weekly.  About 4 weeks ago I began having left side back pain in my upper back on the left side right next to my shoulder blade.  This pain came on gradually and intensified.  It was releived somewhat with massage.  I also began experiencing some pain in my arm and hand. About two weeks ago I would get a tingling feeling in my upper back and arm and pain. It usually starts in my upper back around the shoulder balde area, then travels under my armpit and down my arm and my arm felt weaker.  The tingling is now gone, but I still have upper back/shoulder blade pain and arm pain. The pain ususally starts in my upper back, then under my armpit, then my upper arm feels tight and starts to hurt and the pain then radiates down the front of my arm, under my wrist and sometimes into my hand. And I still feel as if my arm is weaker. Last night I had some muscle twitches in my shoulder and when I lean back to stretch my upper back my shoulder does hurt some.  Although the pain from my back never goes into my shoulder. I can still do my usual tasks, but my arm becomes tired from them  quicker. For example, today when I was using the weed eater my arm felt extra and afterwards when I went in  for a drink my hand and arm shook lifting the glass.  This did go away though after a few minutes. For some reason I have become very concerned about ALS. I did a symptom check and it came up as one the diseases. I am not too familiar with the disease and wanted to know if any of these symptoms should have me concerned. I should also note that I am a very anxious person.  I am taking Buspar and 800mg of Ibprofren.  I went to my MD last week about the pain and weakness and he performed some strength tests on both sides and reflex tests.  He assured me that I tested out fine on these and believes I have a pinched or compressed nereve. But for some reason I cannot quit worrying.  Thank you for any reply you have.