hi dear,
without a physical examination there’s nothing to build on.
on the other hand, I am interested to know your sex (male/female) simply because in my practice I have had a patient with similar complaints; who eventually had a mammogram and was found to have fibroadenoma in the left breast and a small cyst in the right breast.
the reason why I wish to share this is because most physios always count on musculoskeletal causes ONLY;
muscles and bones — due to overexertion, inflammation, muscle tear/scarring, costochondritis etc.
nerve - due to nerve entrapment/impingement, nerve tumors such as neuroma, spinal nerve root compression, neuropathy and/or pain originating from intercostals, pleura etc.
well, this is just an eye opener, so kindly keep your options open and follow up accordingly.
cheers,
thomas