Neck/clavicle pain: thoracic outlet syndrome?

For many years I’ve had the following issue: if I do a hard climbing move involving pushing down, especially across my midline or overhead (eg: crossing through to a hold you have to press or palming an overhead sloper on slab with smeared feet) I’ll get an intense shooting pain at the front right side of my neck (sort of at/under the clavicle). It feels a muscle is catching on my clavicle and I can 'un-catch' it by rolling my shoulders, which generally reduces the pain (though it'll be sore after, there won't still be the shooting pain). 

I recently had this issue return with a vengeance after a number of cold bundled-up hikes and a strenuous bouldering session - I now trigger it with much less effort and it feels like it's causing me to strain my neck muscles. It's also a lot worse if I spend a long time looking down (at a book, phone, or just lying in bed with my head propped up). It matches with thoracic outlet syndrome mechanism-wise (and an orthopedic visit last year netted that diagnosis) but I’ve not heard anyone describe the painful neck sensations that are my primary symptom so I’m a little doubtful. I don’t have any numbness in my arm, just a painful catching sensation where my neck meets my collarbone whenever I look down or make a mantle motion.

I would like to be able to climb without thinking about this and to be able to do other activities that aggravate it, like kayaking or biking, so getting the right diagnosis to prevent this from coming back in the future would be ideal. Anyone else had similar symptoms and found a solution?