Damn. I don't have any experience with this product, but I wanted to say I'm really sorry yours was so bad! And I'm sorry that when you were looking for help and advice you basically got a PR campaign for the very product that hurt you 🙄 that's such crap!
I hope your scalp and hair heal okay in the end, and that someone who has experience drops by the thread with an answer for you.
I'm sure the dermatologist can help. Contact dermatitis is tricky, you can get sensitized to one chemical but then your skin reacts to other things! So maybe it's not that it caused permanent damage but your scalp can't calm down.
Doctor. And yes I would say your hair is very likely to recover once the scalp does. The hair itself is dead, it doesn't really matter how fried it is, as long as the scalp is healthy it will grow back.
It sounds like you have contact dermatitis, you are allergic to the shampoo you were using. I'm not a doctor, but I am glad you are going to go see a doctor. In the meantime maybe some antihistamines and/or hydrocortisone over the counter at your local store can help.
I'm pretty sure once the allergen has been eliminated that your hair and scalp will recover. It's probably not worth buying new products yet until the doctor can look at you but if you need products that are more friendly (fragrance free) to eczema and such in the future, there is vanicream/free and clear. Sorry this is happening to you. I had dandruff before and I thought that was really bad, a medicated shampoo prescribed by my doctor was able to clear it so I am hoping your doctor can do the same for you.