After all being said Why did unemplyment denied me benefits??? please someone one explained this to me.?

I work for this company for 10 years. Last November while pregnant was out for 2 weeks because I had bronchitis. I give birth the end of January 2011 via c-section. Two and 1/2 months later I had return to work because I kept getting calls about how I needed to return to work as soon as possible because my FMLA time was about to run out. May 15 2011. I was injured while I was at work; my back went out on me while I was helping a client to bring into his room his laundry bag up the stairs. Ambulance was called and I had to be taken to the E.R because I could not walk and was in a lot of pain. I was set to return to work 6/5/11. In the mean time I had given my doctors notes to the manager from the hospital and another doctor’s note from physical therapy. What had happened with my back is that a ligament in my lower back had shifted according to PT. On May 22nd I had to make another trip to the E.R because again I was in excruciating pain, and was given a doctor’s note to return to work 5/29/11. I started going to PT 5/24/11. Unfortunately I got into a car accident on 5/31/11. I and my first son 3yr old were injured. I call my former manager the next day after the accident and explained to her that I was in a car accident, and originally I was scheduled to start work June5th but I won’t be able to and that I have a doctor’s note from the E.R which I fax to her on June 2nd, explaining that I would need to be out for a few days. During the conversation, I could hear the frustration in the manager's voice and I felt she didn't believe that I was in a car accident. She then just told me, well ok I will let human resources know, feel better, then we hang up the phone. June 4th 2011, one day before I was supposedly scheduled to start work, I got a letter from the company stating that I am now removed from my full time position due to my own serious health condition and that as of June 6th 2011 my position was no longer available to me. No one contacted me nor even gave me a chance to argue or to even save my position. The note continued on to say that I would be place in a relief position {relief means, I would be contacted for work when needed}. June 6th 2011 I called Human resources of that company wanted to speak to the director who is in charge of hiring and firing people, would not even speak to me and had redirected my calls to the director of benefits and compensation. I scheduled an appointment the next day with the director of benefits. During the meeting I ask her who's decision was it to removed me from my position, she told me, when she spoke to my manager she was under the impression that I told the manager I was not coming back to work indefinitely, I responded to her, I never told the manager such thing. I then went on to ask her will I be able to get unemployment she responded "No". And that I am still employed but as a relief employee. I then went on to say to her, relief is not going to pay my bill and after 10 years of my services, working all crazy hours almost all holidays working for them trying to help them out when they are short of staff, could I be treated in such manners. She told me well “get a doctors letter giving the dates you are able to return to work and we will activate you on the relief list. I simply told her ok, and then I exited the room. Originally I had an appointment to see my PCP on June 8th 2011. I was given a not to return to work June 12th 2011, I purposely never sent that letter to them because at that point to me it didn't matter anymore they had "fire me" from my position, and that started June 6th my position was not available to me. When I spoke to a former co-worker of mine, He told me they had already given my position to another employee that was working there. I file for Unemployment anyways, I recently got a call back from unemployment telling me they are refusing to pay unemployment because I “Voluntarily quit", It's not true, these people made the assumption I was in poor health, and not given any chance FIRED ME. With all that being said my question to you is with all information given will I be able to file a law suit against that company? How am I going to let unemployment see and understand my side of this story. I am desperate for answers here.