Hi cleo
You mention that this has not been bothering you the whole time, just the last 3 weeks. So, let me ask you: are you aware of any tightness in your neck or shoulders at any other time in the yoga class or indeed outside of class? It is only on one side but still I will ask if perhaps you strain to get your head comfortably on the floor: you may have a bit bust (but really that would probably affect both sides but it is worth mentioning just in case the comment inspires a response).
My thought is that you may be hunching your shoulders in many poses including but not limited to the ones where your arms are up over your head. Or in poses like Standing Bow or even Rabbit you could be holding on through your shoulder instead of allowing traction to stretch out that area.
In the meantime you could rest your head on one of your bent arms to see if for the moment it stops it bothering you. Then we can get on with the business of working through your technique elsewhere in your practice.
Namaste
Gabrielle 🙂
