honestly? ask your doc for a simple referral for a good contrasted MRI to be done on your c spine area within your neck? the thing being, that you are NOW showing bilateral symptoms, both sides are now involved so this HAS progressed? this would be the most "logical' place to actually look for a potential issue like with what can occuer with a good herniation, or even large bone spurs that can just create themselves and enlarge over time that would probably be more 'centrally' located only becasue the symptoms are now in both arms/hands? anytime we suffer a shoulder injury or just wear and tear and a life of heavy lifting, the c spine CAN very easily start showing it in MANY different ways. mine did, and so did my rotator cuff a few years later that just WAS also wear and tear too? but just based upon your progressing symptoms, you just DO need a look into that c spine.
one huge thing that i found out just how my c spine herniation prewsented itself along with what was also symptoms of a tearing tendon too,is the symptoms for both can at timers really seriously 'mimic' each other as well since all the nerves that innervate our arms and hands also have to pass thru that shoulder too? believe me, what i "thought' was a possible L rotator issue over the past few months(since my R one was soo bad a couple years ago, i just figured), my PT said is actually coming from my already known stenosis i just have on the L of my c 5-6 vertebrae. stenosis forms within the foramen where the nerve roots go out from the spinal cord and can become impinged from that or other things too? ya never know anything about any given area of our bodies til that good in depth look gets done. trust me on that one.
but push your doc for that contrated(just helps to better highlight certain findings)MRI done on your c spine. given your progressive symptoms you have had there and do now, honestly, its kind of a no brainer for your doc to actually WANT to either rule that area in as the problem or rule it out. but it seriously needs an MRI at this point. this is just the MOST 'likely' area where your symptoms could be even coming from on both sides. good luck with this and do please keep me posted. FB