Can A company terminate or discipline you?

[Sheba/ A.J]

I have a disability and missed a few non consecutive days at work (4) I was sick due to my disability now since I have 4 unexcused absences in a 6 month period they want to discipline me or even terminate me for the absences I was wondering if this is even legal and if i would be protected under the americans with disabilities act. please let me know if Wal-Mart has a leg to stand on also even if they do there policy was 6 days in a 6 month revolving period and i just found out today that there policy has been updated and no one has told anyone anything about the updated policy

Thanking you all in advance for any information you can provide