You say you've washed your hair, but not what you've used to wash it. If you haven't done a silicone-free sulfate clarification, it's possible that may help, though it's quite possible that you hair sustained damage which will need to be grown and cut out. Try using J&J Baby Shampoo or one of the Suave Naturals or VO5 Herbal Essences shampoos once (if it's going to help, that's all it should need). However, if the hairdresser missed that section when applying heat protectant, or used a high setting on the flat iron and that section got subjected to 320F or above, your hair may have melted into that formation.
Peace,
Morgan

Baby Fine 3B, low porosity, normal density and elasticity
CGing since July 2008