Mam, seems like you have a shoulder sprain which could be caused by carrying your child, mam i would request you to take an xray of shoulder ap view and then show it to a orthopaedician, there are some tests to be done for now give your shoulder lots of rest and take warm salt packed in a cloth an place it around the shoulder, an after that apply dicloran gel and apply cold package, in addition to this you can start with tab hifenac mr twice a day for five days and avoid picking up heavy weights and you must be fine by one week.