On herceptin and perjeta , stage 4 , itchy skin and now itchy scalp -anyone treated itch sucessfully

I have a lot of itchiness!! But I'll ask you; does it come and go? If you distract yourself, can it sometimes ease? I've seen 2 dermatologists and I was diagnosed with 'cutaneous dysaesthesia'. It's worse at night, worse with heat. It's spreading over time. It's nerve related, so topical creams don't really help. Started on upper arms, now on neck, down arms, back