A.P.
Contact their parent company, Amscan Holdings, Inc., and ask for their commercial liability carrier's contact info, or their third-party administrators (TPA) contact info for their commercial liability policy. I would not give them many details, just say you need the contact info. I did a quick Google search and got this info:
http://www.lead411.com/company_AmscanHoldingsInc_Rittenbe...
Again, give as little info as possible, just ask for that information. Even if you email the CEO, don't dwell on your story (though it is quite sad, they should have given the info to you before you left the store). You might want to do a more thorough internet search for that info as well.
At the end of the day, you just need to set up a liability claim against them since you were injured in their store. You don't need any attorney for that. If you are still having trouble and/or you will have to pay out of pocket and then they reimburse you, you may then want to get an attorney. See what you can do for free, first. Good luck!