Pains in chest could be from a myriad of reasons including muscle strain from physical activity, hiatal hernia, spinal problems, or other reaasons...yes, including heart. Honey, do tell your parents or another adult that would be glad to help you have someone check you for the cause so you can enjoy being 15. Blessings and hugs to you! Let us know how you are...we care and are so glad you asked us! : )