I am in the front end and my head cashier basically told me to permanently injure my back for the good of the company, denying me going home when I am in too much pain to continue work.

I am over 300 lbs, diabetic and obese. I have attempted to lose weight to no avail due to the fact my medications have weight gain side effects. The management at my store knows I have a bad back with spinal bone spurs. I have even acquired a doctors note to be able to sit it in too much pain.

My head cashier has ignored that note. She has repeatedly told me to keep working, and for the last three months, I go home from every shift in tremendous pain. Today it got so bad I considered leaving early. My request was denied and the pain has steadily gotten worse to the point I can no longer even do basic job functions.

What should I do?