How to get this weird gross greasy look out of my hair!?

OK I don't know what it actually is, but I have this gross greasy look in the mid section of hair in the back. The only products I use are shampoo, conditioner, hair syrum, heat protectant (spray), and a little but of hair spray. I use a flat iron daily, and lately I've been air drying it instead of blow drying. I asked my friend's mom who is a hair dressor what to do, and she told me to just shampoo it (no conditioner) and it should come out, but it hasn't. What should I do? It looks and feels greasy, but it also has this weird dried syrum feeling to it (kind of waxy feel?).