Hey mom,
I am not a doctor but sounds pretty normal,
the exterior pain is probably from your bra, when your pregnant everything moves around. and the baby grows pressing and squishing everything UP and OUT LOL
The burning inside is probably indigestion, and some tums might help that.
as for the bra, try going to victorias secret, they can measure you and fit you for a new bra size.
If you think its not your bra, then it could be sweat pooling in the area, causing an irritation.
If you don't think its indigestion, then it it more likely just normal stretching from the pregnancy.
I suggest calling your Ob GYN and talking to the nurse, tell her what your symptoms are and she can advise you,
I have been pregnant 4 times, and with each pregnancy, pain pain pain, al kinds of weird places LOL,
No one ever tells you about that, the most they ever talk about is the pain of child birth, not the 9 months of weird strange scarey little pains, everywwhere.
Good luck and congrats!
M