Why did my gerbera daisy wilt overnight?

My boyfriend brought me home a potted gerbera daisy plant. Yesterday it looked really good, lots of flowers, several new blooms, and lots of big green leaves. I know nothing about plants so I went to a website and did everything it said. I put a few drops of plant food on the soil, watered it (but not directly in the crown), misted the leaves alittle, and had the heat on low. Well I woke up the next day and the whole thing has wilted! The blooms look okay but the stems and leaves look pathetic. What did I do to it??