Horrible scalp condition; anyone else?

UPDATE: I’ve been informed that my symptoms don’t really match up with my diagnosis and I might have been using the wrong treatments entirely (which could be why they aren’t working). Thank you everyone for your help!!

I’ve had a very bad case of seborrheic dermatitis since I was a little baby. I’ve been to dermatology multiple times and usually get a recommendation for Head & Shoulders (which im allergic to, by the way) and then a few prescription shampoos. Nothing has worked. I am allergic to all of the prescription shampoos due to their ingredients. The steroid creams do nothing as they only momentarily stop the itch, not treat the condition itself, and they result in extremely greasy hair and worsened symptoms. I’m not eating anything that I am allergic to, nor are any of the ingredients that I am allergic to in my shampoo.

Im curious if anyone else deals with this, because I know EDS often involves skin issues and skin related comorbidities. Advice encouraged, Im literally going nuts from how severe the itching is. Im even considering visiting dermatology again despite the fact that they have given me exactly zero useful information. Ugh.