Hi For A Few Weeks Now I Have Had A

Hi for a few weeks now I have had a really itchy head and I looked into it and thought maybe I have got just an itchy scalp from dandruff but that doesn't seem to be the case as I have continuously washed my hair and the day after it still feels very itchy. Then I considered that it might be sunburn because I have recently moved to a more humid climate and have only just gotten a hat. But I haven't been in the sun much at all in a few days and the itchiness seems to have spread down to my back and neck although there doesn't seem to be any rashes it does burn quite a bit and look red. Not only that this morning when I woke up I noticed a red rash just above my chest which isn't itchy at all but it's quite red and not raised. The itchiness is so distracting that I can hardly concentrate in classes and have to constantly remind my self not to scratch. I do have allergies to things but am aware of what I'm allergic to food-wise. I haven't changed my shampoo or conditioner either. Can anyone tell me what could be going on? I'm hoping that I'm overreacting but wanted to check. Thank you.