Firefox, I've never seen that conditioner in the US. Maybe it isn't as popularly avaiable here?

OP, I think you should maybe just try phasing products in and seeing how your scalp reacts too them. Because you don't know what your scalp is reacting too. Like, after your scalp has recovered you can try one products (probably a conditioner) for a couple weeks and see how well it works. I don't know if this will be helpful, but here's some stuff on NC about allergies:

Top Hair Care Product Allergies

I hope you feel better soon!
Fine Texture, Normal Porosity, Normal Elasticity. Dyed to brown a few months ago.
Trader Joe's TTT Shampoo
Rinse Out:
Yes to Carrots, AOHR, Aubrey Organics Rosemary Peppermint
LI: Yes to Carrots
Stylers: Shea Moisture Curl Enhancing Smoothie, LA Looks Sports, Suave Professionals Captivating Curls Whipped Mousse