Hello, a lump in the middle of the chest between the breasts is usually not breast tissue. It is more often a skin condition such as a cyst, a boil, an ingrown hair or scar tissue, or sometimes irritation of the chest-wall cartilage. I can't confirm the cause from photos alone. Please avoid squeezing, pricking or applying home remedies, as this can cause infection and scarring.
Next Steps
Get it examined in person soon if it is painful, red, warm, discharging pus, growing, or if you have a fever. If it has stayed for more than 2 to 3 weeks, it is also worth having it checked even if it doesn't hurt. A teleconsultation on Practo can help me ask the right questions, review clear photos and tell you whether you need a procedure, ultrasound or just treatment. – Dr Amandeep Aggarwal, Family Physician, Sangrur