My breasts have been itchy the past 2 weeks. What could make breasts itch?

Many things. If your bra is new, you could be allergic to the material, or to chemicals that are sometimes applied to new clothes. If you're using a new soap, or clothes detergent, or fabric softener, or applying a new cologne, it could be any of those. If none of those possibilities fit, let a dermatologist examine you - you may have a subtle rash that will lead to the answer.