As its come on suddenly, you sure its not a ligament injury?
Rest is suggested but I’d really like to know what caused it.
I am not a physio, but I’ve been to a few, and within the last week. The guidelines I’ve been given is a short period of rest, no more, and not a long sustained rest. I’d assume it depends what is actually happening, but with the injuries I’ve had, total rest wouldn’t fix anything, just get the initial inflammation/pain reduced. The actual fix is just better physical control, increasing range if its limited, and strength training.
I cant recommend getting to a good physio or sports therapist enough tbh.