I have a lot of itching on my body forming pimples, specially on my lower abdomen. i have a cat, but he doesn't have any fleas. what can it be?

See a dermatologist: Or other doctor who is familiar with skin lesions. Without seeing these impossible to diagnose over the internet.

Itchy red bump dz: You probably have folliculitis. It is very common. Don't ditch your cat! your dermatologist might prescribe an antibiotic gel which will work to decrease the inflammation much as we do for acne.