Hello, please help me. The pregnancy is 20 weeks long. For about 2 we…

Hello, please help me. The pregnancy is 20 weeks long. For about 2 weeks I have been suffering from itching. I combed my belly, back and chest - bumps and blisters, it's always itchy and painful, I can't sleep. I have tried many creams and ointments, made compresses with iodine solution, all useless. Maybe someone has encountered this, how to get rid of the itch? What is it connected to? Maybe some tests should be done? Thank you in advance!