It itches when you sleep in one bed, but it doesn't itch when you change it. What's going on here?

Hello, this situation is mostly caused by skin allergy. It can be treated by oral anti-allergic drugs such as cyproheptadine or Kairuitan and topical cyproheptadine ointment. Don't eat spicy food, don't drink, and keep it clean. If you have recurrent attacks, you'd better go to the hospital for an allergen test to see if you are allergic to those substances and avoid contact at ordinary times. You can also use desensitization therapy, follow the guidance of clinicians and wish you good health.