What can it be? a rash (skin colored unless i scratch then bumps are reddish) small bumps on my stomach, chest by my underarms but not on armpits, and navel. been there for more than 6months,not itchy unless i scratch due to hot water or sweat...?

I think you may be dealing with a type of urticaria ( hives) and your skin is in a state of heightened reactivity where scratching releases histamine. If this is it, the cause of this is rather elusive. It may be an allergy to something internal or external. I recommend consulting a dermatologist or an allergist for diagnosis & treatment. In the meantime have you tried taking antihistamines?