Best exercise I have found is roll up a towel long ways. It should be as long as from your neck to your hips. Lay down on a hard surface, I do it in the floor, and place the towel under your back and roll over onto the towel placing the towel right on your spine. Then force your shoulders to touch the floor.

You'll find it in this video.

https://www.youtube.com/watch?v=Z4aXRj0uIj4

It really helps me when I have a flair up. If you have vascular envolvement, you lower arm should be swollen more than the other. Wearing a compression sleeve will help. I wear one everyday.