How long does musculoskeletal (shoulder as well as below collarbone & above breast with no breathing/heart issues) pain usually last and how can you tell if the treatments used are working? when, if at all, should i contact the doctor again?

Basics: The answer would depend on the type/extent of the injury & the amount of tissue involved. This would be best answered by the treating team who have all the information as the posted info is not adequate for a response. Gradual relief/improvement in pain and/or decline in medication use would suggest improvement. You should contact the doc at any point you are confused about your situation.