Welcome to HCM.
Since you had your Last period on 7th June, pain is not related to periods. Probably the padding of the bra may be causing the pain.
If there is no redness
in the area of pain or any palpable swelling in the breasts, then you do not have to worry. Use more comfortable Bra.
If there is fever
or the pain is of persisting character, then it would be better to consult a surgeon, for examination and management.