Little rash on parts of neck, back, stomach & under Breast. Itchy at times, put chrotozone cream on neck and helped that spot. What could it be?

Rash. If you are otherwise well, it may be something you were exposed to. Have your MD take a peak at it and give you an answer. All the best.
Could be. Many things... Heat rash, contact dermatitis from detergents, yeast infection, etc. I would suggest switching to perfume and dye-free detergent and bath soap, using the cortisone 1-2/day, and if it does not resolve in 3-4 days, have a doctor check it out. .