Hi,
It sounds like the beginning of frozen shoulder to me, that's how mine began, first in the left side and now am feeling it in the right. See a doctor asap and a physical therapist. I gained back a lot of my range of motion, but still in pain from moderate to severe at times. You may want to try liquid joint supplements, they work better than pill form. This is starting to happen to my hair stylist too from the continual hairdressing. The sooner you treat it the better. Otherwise it can take up to 3 years by doing nothing I've heard. I hope this helps.