Sonic Drive-In

I stopped in about 3:30 for half price drinks i got a cherry limeade my bf got a coke i drank about 1/2 on the way home. I live in Troy. When i got home i took the lid off so i could get the cherry and lime out. To my surprice something white and foamy was floating on top i went to scoop it out and it was slimy and gross what do you think it is? It is still clinging to the side of the cup. Im sick to my stomach. Im hiring an attorney