My workers compensation claim was denied even though it was a wrk related injury what can be done to overturn this decision?

I injured my foot and hip at work on 5/9/16. I was given injections and told to stay off of it and if it didn't get better by Sunday to let the safety person know. So on Sunday I texted the safety person that I was in a lot of pain and couldn't walk on my foot and I needed to see a doctor he said he would try and see if it was possible for me to see a doctor but to go to work. I did go in and an hour into work my foot gave out and I fell into the side of my work truck and knocked myself out I came to in the ER and had bad pain in my foot, hip as we'll as my head, neck and upper back. From the time medical services got to me and finally recovering an hour or so in the ER i couldn't remember anything including name, DOB, SS, where I worked etc... but everything started to come clear and I remembered everything and told the ER staff and doctor what happened and the ER report says exactly what I told them but WC is saying there's nothing to support that it was cause of the 5/6 injury