I took four weeks off of work - which was a low-key mostly-sitting desk job - and wished I'd taken more. The fatigue was killer, and also, well, sitting was a problem for at least a couple months. Slowly improving, but I don't think I could sit for hours on a hard surface for at least 6 months! I could sit for most of a day in a very comfy desk chair by 3-4 months, but since you may not be able to control the hardness level of chairs in your classrooms...
Honestly, I couldn't have managed to concentrate on anything for that first month. You can go back to school, but you may not do as well, with the exhaustion and distractions of pain/dilation/etc.