A single red, burning bump that appeared suddenly often is a local skin reaction, an insect bite, or a small infected hair follicle, rather than anything breast-tissue related. The burning when you press it fits that too. These usually settle within a few days with simple care.
Health Tips
See a physician soon if the redness spreads, the bump grows, you develop fever, or pus starts forming, since that needs a proper look and possibly treatment beyond home care.