You may have protection under the Americans with Disabilities Act and state law equivalents if your hours were cut and you were terminated because of a disability or because management perceived you as disabled after you collapsed.
An employer can fire you for any reason, including no reason, as long as it doesn't include anything in the "protected classes" which include:
Gender Identity or Expression
Like Nicholas mentioned, there *may* be something related to disability here if that was impeding your employment, but it doesn't jump out at me. Actually your comment clears up a lot, since there was the issue with the storage boxes, and they *can* fire you for that or anything related to it without any recourse for you.
Clark County, Nevada practitioner.