Toddler itching at night!

Hello mummies! My son is 2y.o and he is been suffering from itchiness at night! He itch till blood..we went to see different doctors and dermatologist..even was in kk hospital, followed all the instructions by doctors..went tru 2 courses of antibiotics in 1 month!!! Lots of steroids creams!! During taking antibiotics he was better but after antibiotics finished all returned again..we didnt sleep for about 3 months..he cant go to kindergarten...please advise if anyone had this issue and how did you treated it??? Aside from this we tried to avoid allergic food like gluten, eggs, dairy etc..we even tried TCM..non worked! Doctors in kk hospital did only blood test that's all..non explanation been given rather than atopic dermatitis..but I have a feeling that the problem is somewhere else..