Unfortunately what you're asking isn't really the sort of thing we can provide advice on - for the simple reason that it's very much a medical question that relates specifically to your condition. The injury you experienced sounds awful, and I am very sorry you have to deal with this - but it would be very irresponsible for anyone here to try and advise you on how to approach this. It really has to be asked to a medical professional who understands the nature of your situation, and who can tell you what kinds of activities are okay to do, and which ones might cause you greater trouble in the future. Until you're able to get that advice, I'd suggest not drawing from your shoulder, given the discomfort you're experiencing.

If your physician feels using your shoulder in this way will exacerbate the issue and should be avoided, there's really no choice but to use your elbow instead. While this isn't ideal, it is still workable and will not preclude you from learning to draw. There will simply be some longer strokes that will be more difficult to execute. It's not something I'd recommend for someone who is able to use their shoulder without risk of aggravating an existing injury, but it's also not a deal-breaker when it comes to drawing. The majority of the strokes we execute in the course of a drawing can still be performed from your elbow - in this course we push for using the shoulder to ensure students aren't blocking themselves off from full use of their arms. Medical concerns are definitely another story, however, and are an entirely valid reason to modify how you follow along with the lessons.

Ultimately, every student needs to take the material, and the feedback they receive based on their results, and understand that it's given based on an ideal situation. It is in some cases, such as this one, necessary to look at that feedback through the lens of your own situation. But absolutely do not force yourself to apply the material without considering what is very clearly a serious situation resulting of considerable injury.