TL;DR Quit a job in Jan without giving a 2 week notice due to stressful working conditions. Was hired at VA, questions about my background check as I had said I quit, previous job saying I was fired.

In Jan I quit a job without giving a 2 week notice. I gave them a notice that the day I quit would be my last day. The reason I quit like that because there was so much stress and I just had a mental break. Looking back I realize it was the beginning of a severe depressive episode. I had some personal and financial issues going on at the time and had been working a lot of OT because we were short staffed. In May I applied for a job at a VA hospital. I was selected and did all the paperwork. In August I started. This past Friday I received a call from someone in the office of security and personnel management regarding my background check. He asked me why I had been fired. I told him I quit and told him I gave notice the same day I quit. He asked why and I said I was under a great deal of stress. He asked what kind of stress and I had a bit of a hard time verbalizing it. He said he would have to call the person he spoke with back. I called the HR at my previous employer and the person I spoke with said I was involuntarily terminated (this encompasses several scenarios of termination). I honestly had never done this before and did not even know that was a thing. I honestly was not trying to deceive them or anything.

My question is has this happened to anyone else? What was the outcome? Is there anything I can do to fix this?

ETA: changed from security clearance to background check since I don’t need a typical security clearance. I can’t change the title.