Is there some particular reason why you are suspecting that your daughter is having fat lump on her shoulder? There are few causes for the lump.
The first thing every doctor is saying is an
enlarged lymph node and it usually is. Lymph nodes enlarge when there is
inflammation or infection in the region drained by them.
I think it would be best to take your daughter to the doctor so that he can do some blood tests and ultrasound of the lump. After that your doctor will be able to determine what is in question and he will be able to determine the right treatment.
Let us know what has happened at the end with your daughter.