If it's not a rotor cuff then it may be a C5/6 disc herniation. The symptoms are similar. Perhaps if you had seen a neurologist they might have provide a different diagnosis. An MRI scan will answer the question.
Mine has recently flared up and so I am back on anti inflammatories and pain killers. It seems to be calming down and should be gone within the next couple of weeks.
When you do get the diagnosis and treatment plan then have a look at the Bob & Brad physio advice on You Tube. There's lots of good advice there.
https://bobandbrad.comIn terms of managing my condition the single most important change I made was to use a standing desk both at work and at home. Actually at home I use a standing shelf, but I can tell you more about that later.
In terms of cycling, yes I continued to cycle. In terms of my position on the bike then the best change made there was to ensure that my back was as long as possible and to have relaxed shoulders. A shorter, higher stem was not the answer.
Good luck, keen to hear more from you.