You should practice back rolls with a lower 'X" across your back.
Just like front rolls, shoulder to opposite hip, back rolls employ the same technique, unless you are doing gymnastic rolls over your head with both shoulders and both hips making contact, then that effort needs a strong neck and well rounded body.
But ... do what is called a bad back roll by rolling across your back until you can strengthen your neck, or your neck heals sufficiently. This method will also allow your self confidence to return as you mentally remember you are not doing the best rolls while you heal ... physically and mentally.
Good luck. Good practice.