Contrary to common belief, you *can* be fired due to a medical condition if--1) You missed work, even for a medical condition, without a) using earned PTO to cover the absence; b) and/or being eligible for FMLA leave and using it for the absence--but since you had only started working there 3 weeks earlier, you would not be eligible for FMLA and likely did not have PTO for any time you missed.2) You cannot do your job, even with some "reasonable accommodation," like some change in rules or procedure or some assistive device, which change or device is not too expensive or disruptive to the employer. Examples of a reasonable accommodation include letting a person who ordinarily stands for work (like a cashier) have  a stool to sit, if the work can be done sitting; letting someone with ITBS have more frequent bathroom breaks; getting an ergonomic keyboard for someone with carpal tunnel; etc. But if part of our job was working in the warehouse and you simply could not do that because it was "too risky" you could be terminated for being unable to do the job even with an accommodation.So if either 1) or 2) apply, terminating you because of your condition  is legal. If neither 1) nor 2) applied, then this may have been illegal discrimination against you due to a disability or medical condition, and may wish to contact the federal EEOC to discuss whether you have a valid complaint.