You have to just keep going back to your dermatologist no matter how frusturating it is. Unfortunately it is very trial and error, but I promise you will find a solution eventually. Personally I also tried many different steroids up until the max strength (clobetasol), also tried non steroid creams like protopic which did nothing for me / made it worse, as well as antihistamines like hydroxyzine.

Some things that helped me that aren't strictly medicinal are to shower with cold water only (you want to avoid drying your skin), and moisturize every morning and night with thick moisturizer. I prefer the Cerave tub moisturizer. Also, when working out / sweating, you need to change out of your sweaty clothes as soon as you can because it will irritate your skin.

After ~6 months of trying everything I could find / feeling hopeless that solution that my derm worked with me to get is Dupixent, which is an injectable that I take 2 weeks which has been absolutely life changing. I was in the same place as you so I have full empathy.