I went thru something similar to this after my gallbladder surgery in June 2013. I thought I would lose my job due to being unable to perform my job up to par postop. I did not lose my job. I'm still there. It's a shame. Employers really don't care about a worker's welfare, they just care about results. All I can say is follow your doctor's orders, take care of yourself, and do your best. Document everything. Have your doctor's work orders in writing. That way if the worst happens and they fire you, you will have some leverage with the unemployment or HR office. Best of wishes.