Terrible pains under the rib cage..no doctors giving me a straight answer to what the problem is..HELP please?

i'm a 15 year old girl student, who has been having these terrible pains from my sides the whole way across the muscles below my rib cage for a little over a year now. I have been to two GP doctors who have both given me muscle creams and painkillers and told me to rest, but this hasn't worked. i ended up in casualty in the local general hospital during the week and they have prescribed buscopan for me to take for three days. i am a little worried that they can prescribe me tablets when they don't know exaclty whats wrong! If you have any information that you think might be useful to me please let me know thanks :)