Fired for calling OSHA

Hello, I was fired on July 11 2013 after returning back from vacation. On June 26th or 28th I had filed a complaint with OSHA regarding unsafe practice my employer makes its employees preform. The day my boss got the letter from OSHA he called several employees to ask if us or anyone we know called osha. He said he was required to do so by law. After returning from vacation on July 11 I was given a termination letter dated July 3 2013. The letter stated no reason. I also asked my boss via phone what the reason was and he said there was none. I filled from unemployment and was denied because he said I caused damage to property which I did not. I also have my pay stub showing where health insurance was taken out in July but have a letter from insurance co saying insurance stopped June 1. I have filed a complaint with US DOL whistleblower protection as instructed by OSHA. What evidence can I get to prove I was fried for calling OSHA? Also do I need an attorney? If so would it be possible to find one that worked and got paid only if the case was won?