I have dark spots under both breast looks like a bruise have not been hurt or been in any accident currently not allergic to anything what can it be?

Dark spots? Women who are allergic to the metal in an underwire bra can sometimes develop chronic discoloration to the skin. The reaction is caused by allergy to nickel. This is a contact dermatitis (which is different than an environmental allergy). I might suggest an over the counter topical steroid cream and using a plastic underwire bra (if you were them).