Usually the numbness and tingling is Hypo and I would go as far as to say that is what has happened in your case (personal opinion ..not a Doctors).
I had to stop my T4 med for 4 days because of palps and hyper and I too have had the tingling and numbness.
Stopping the meds has caused my TSH to go from just over 1.0 to 3.48 in a week so I would guess thats whats happening to you.
If you found a pharmacy that still has the Armour and you plan to continue using it, be advised, they will soon run out! This is a fact. Tell your doc about this and try to get a multiple month perscription If this other pharmacy still has it. A lot cheaper then compounding. Lets hope Nature Throid (like Armour) gets their ball rolling in three months!
Chances are that your doctor knows very little about the FDA haulting Armour production, my docs nurse was giving me a hard time about it. She did not believe me.
Not taking your med can do weird things, no one here can say this is the sole reason for the arm pain but might be part of the reason. At least its not the left (heart) side!
Take care
Armour production has been haulted by FDA. They reformulated in Feb. without following FDA protocol. May not be available for along time,who knows??? We were not doing well on the new formulation of Armour( weird HYPO symptoms and blood work off after our last refill) anyway and had already switched to Naturethroid 5 weeks ago. However, they are having supply/demand issues and it is also hard to find. They will have supplies filled in aprox. 90 days. You can have compounded dessicated in your MG to hold you over until then. Naturethroid is working great here. You should try it when you can. It seems to take more then the Armour however. The conversion chart is a little off. We are on 1 grain more so far, and will do labs in 2 weeks.