Hi there, First I would make an appointment with your doctor to see whats wrong, it might be that a chiropractor could be a wrong choice depending on whats wrong, so i would definitely start there.
In the mean time I would recommend a heating pad to start with. I use mine every night and it helps bring the pain down a little. Also ice packs can also provide some relief and it would help decrease any swelling. Good luck to you hon.
You should see a chiro. or a dr about a breast reduction. I know those may not be options now but neither would a herniated disc. You may want to try a more supportive bra. I know there are some shops including Victorias Secret that for a fee will measure etc and find the exact type of bra you need. Also a back brace may help. I know people especially guys think big boobs are fantastic but they do not have to lug them around! Best wishes, Sissie