"chronic back pain and unexplained weight loss"

i have been going to royal manchester childrens hospital for about three years now and i am very disgusted with the support and help i have recieved. i am 16 and have been suffering with chronic back pain/spasms and unexpected weight loss/gain since i was 14, the doctors told me it was unusual at my current age and they told me i could see a physiotherapist, a nutrionist/dietician they also said i would see the gastro team and have a biopsy and have a colonoscopy i have only had an MRI scan which they said my back was completely normal! if that is the case then i dont know why i am having such bad pains it is hard for me to lead a normal teenage life when my back literally feels like it is falling apart, i cant sleep at night and also when i wake up it is the worst. i have always wanted to complain about their services. i never get enough attention and have had so many health issues in the past 3 years, everytime they give me an appointment it is a long wait and i cannot bare the wait's any longer, having chronic back pain and unexpected weight loss/gain makes me feel depressed so my health is detoriating even more, i get sick and tired of the hospital telling me the same stuff, they keep telling me my back is fine, but they cant feel the pain i am in, i have tried numerous amounts of medication but they failed to ease my pain, i had the worst time during my GCSE's as i was constantly out of school going to appointments that made me feel worse as they kept telling me that i am fine!, it is unreal how much my back hurts and they cannot do anything about it, they have never really tried to investigate any further and i just want to get rid of my pain and just be normal! i always thought that doctors could support me and help me but 3 years ago my oppinion completely changed, i dont have support off anybody as nobody can understand my pain nor do they know how to support me or ease my pain, this has caused problems with my relationships with loved ones and all my concentration, i have set days within education where i cannot physically sit on the chairs as my back is hurting so much which then causes more problems at college, i am beginning to think that nobody is out there that can help me in my situation, so that is why i am writing to you today so i can receive help and advice on what to do and who i can see.