Welcome to HCM.
Thanks for writing in.
The condition can be pressure urticaria
Certain types of cancers can present in the way described by you.
Pressure urticaria is the one in which itchy rash
appears on areas of pressure and gets relieved on its own after some time.
A proper examination and blood work up would be needed to establish diagnosis.
Consult a qualified dermatologist
for proper diagnosis and treatment.
Hope this helps.
Wishing you good health.