When you are riding, try to remember to keep your elbows pressing together rather than flaring out. You cannot hunch your shoulders while pressing your elbows together, hence, you upper back/neck problems will decrease.

If you think about our basic position on a bike - it's a plank! I always recommend planks to my spinning students. As soon as your PT gives you the green light, I'd start those. Or, possibly you can do a modified plank with your upper body on a raised surface.

Those tips were given to me by my physical therapist who is also a cyclist.