What should I do about a questionable firing with no contact?

Hello all. I was recently fired from my job under what I believe to be incorrect circumstances. Allow me to explain my situation... I recently confronted my manager about the possibility of needing to take my short term disability through the life insurance provided through my work. I'm having a pretty extensive knee surgery in a couple of days. I told my manager all about what would be occurring, she acted as though they would do whatever they could to assist me, told me everything would work out. Later that same day while on my shift, my manager asked me to come with her to a conference room. There we met with another manager in my department. The confronted me with what they claimed was my time card. On that time card were several instances of "down time" that I did not take. They grilled me repetitively, trying over and over to admit that I had taken all of the breaks. Something I did not do. After I repeatedly denied and refused to take accountability they left the conference room and came back a few minutes later. At that point they asked me to leave, told me that HR would be in contact with me about the status of my job. It's been about five days. I have received no contact, I have tried to contact my manager with no response. What should I do?