Dealing with Light Sensitivity in Uncontrollable Environments

How do you deal with light sensitivity in a place you can’t control the lighting? I have really bad light sensitivity to the point that I have to wear sunglasses outside even if there’s full cloud cover. My apartment stays mostly dark, tv set to the dimmist it can be and still able to see, just anything to help but there are places like my classes or grocery stores where I obviously don’t have control of the light and I get terrible headaches, nauseous, lightheaded, and it all lasts for hours or even days. I do have glasses and I know there’s a special lens that can help but I cannot afford that. Is there anything I can do besides just avoiding places that are too bright?