I mostly got pain and a general numb/clumsy feeling from around the elbow, down to my hand.

Maybe you have pulled a muscle in your upper arm and it's just making it more painful it's so hard to know.
Unless the x-ray shows up something, it might be a muscle prob

If it is RSI, it can sometimes take a few months of not doing anything to strenious with your arm before most of the ache goes.

I just found that when i had pain in my arm, just to really try and aviod using it to much did help. im glad that seems to be helping you a bit too!

Hope you get it sorted out & dont have to cover everything in ice-packs