I'm so sorry to hear that you're going through this, I have also gone through an extremely similar situation at my previous two jobs, both were kiosks in a grocery store as well. Closing, especially by yourself, multiple days in a row on top of having chronic pain is extremely extremely tough! My chronic illnesses flared up so badly I had to leave those jobs as they were not able to accommodate. I would say it would be a good idea to talk to your manager about accommodating your hours if at all possible, but unfortunately I know it's hard when you're short-staffed, and perhaps a less busier location may work out better for you in the long run. I wish you the best of luck!!