Headcase & Kaska,
The shot generally helps immediately since it contains a numbing agent & the effects can persist, as I said, from minutes to months, if a steroid is included. That said, quite a number of people feel no effect from it except localized soreness from being poked. This type of shot is used as a potential diagnostic tool for ES & can be helpful if it even temporarily takes away the typical, throat/neck pain caused by ES. As you can see from Kaska & SewMomma’s experiences, it is not a totally reliable tool. The injection is often done in the neck, but I’m not sure of the specific location. That may vary according to where the pain is.
Kaska, shoulder pain is a known ES symptom. It can be an indicator that your accessory nerve (cranial nerve XI) is being irritated by the elongated styloids or calcified ligaments. Once you have surgery, that problem generally goes away.
Jules wrote a post in 2016 that covered cranial nerves and ES symptoms quite extensively. The post is long but quite thorough. The information is invaluable for helping to understand many ES symptoms. I’m including the link to her post here: ES Information: Common Symptoms And Possible Explanations For Them