I have severe itching accompanied by bumps, welts, and rashes - scabies or something else?

Could be scabies: You are describing either scabies or eczema (allergy). If you are also itching in hands and feet it is very likely that it is scabies. In that case all medications are prescription based so you need to see a dr. If not you may try otc Hydrocortisone cream + oral benadryl (diphenhydramine).

Scabies: Scabies looks like lines of burrows on skin made with little mounds or blisters. They cause itching which is often worse at night. Although they can be anywhere on skin they like going into skin folds (waistline, axilla, breasts, between fingers, feet, wrists, knees, elbows, buttocks ; genitalia. A dermatologist or your family doctor can make this diagnosis accurately.