Tri this weekend. But, I'm having shoulder and arm pain

[spindizzy]

Excuse my ignorance but why would you see a chiropractor for severe arthritis in your neck?

[KnottedYet]

Especially when it sounds like he fragmented a protruding disc and now a piece is sitting on the nerve to your arm.

Arthritis doesn't do dramatic changes. Arthritis doesn't change in a day or two or in one manipulation. Big changes like that come from discs or alignment. Something went out of place on Sunday. The arthritis is just background noise. (you had arthritis just as bad on Saturday, but you didn't hurt)

Some DCs will deliberately pinch off (fragment) a bulge if there is no other way to relieve the spinal pain. That gets the bulging piece out from between the vertebrae and relieves that source of discomfort. It floats around loose in the neighborhood and eventually the body resorbs it. But that is not a technique to be used on the first visit of a recent problem, and certainly not on someone about to do a tri.

ETA: he may have accidentally torn the disc wall so it is leaking disc goo onto the nearby nerve (like a leaky waterballoon). The goo in the disc is caustic, and when it touches the nerve root it can mimic a compression effect. That wouldn't show up on an MRI. But most good DCs know how to avoid "cracking the egg" like that.