M.P.
READ all before you panic PLEASE!
years ago my oldest daughter complained that her chest hurt immensely and with heart related problems so prone in my family we whisked her to the hospital and asked questions later. the dr of course checked her heart as a precaution.
they took x-rays and all discovered it was not her heart. it just so happened that a sports medicine dr was in the ER at the time and reconized my daughter as a high school colorguard.
he came over and examined my daughter and asked her questions. he figured out that my daughter after months of tossing her flags and other colorguard equipment that her ribs connecting tissues were inflamed. NOW for your part of this message. I am sure that her arms go way up and way down repeatedly when she jumps that she could have hurt the same tissues that my daughter did---- her's was helped with a regiment of antibotics.
ask the dr to check that when he examines her
if this happens to be tha case or even a pulled muscle that other mothers suggested. get her to learn the importance of stretching before she goes on the trampoline.
a note to my daughter's issue. in the summer between her sophomore and junior year she discovered yoga and used that to stretch in fact after her high school career of colorguard she was an instructor for several years and she used yoga with her students and she never had muscle related injuries in the 6 years she was an instructor.