stomach problems

i am writing this as a mother who has really doesnt know what to do for the best any more so bad now is our situation .my son has aspergers he is 24 a twin born 7 weeks early for as long as i remember he has suffered terrible somach pain no matter how often i took him to the doctor as a child they and the school always treated it as him wanting time off school.As he got older the pain increased along with diahorea often days of it until he had to leave college at 18 he became very thin as he ate little and lost what he did eat,we were told he had IBS given Buscopan that did nothing to help.Over the last week 6 years we have seen specialists seen our GP often he now has stomach ulcers and we,ve tried every acid tablet known to man he lives on strong pain killers and spends every single day and night in such horrific pain he rarely goes out as he needs to be near a toilet as a mother to have to watch your child in so much pain is awful and you expect the doctors to see how serious this is and to help yet they are always light hearted and juggle medication saying try this try these nothing works Today my son tells me ive had enough of being n pain every day i dont want this any more !!! we got some more tablets from a different doctor who just happened to mention what we always suspected "on your notes it says you have aspergers that you need mental health " obviously they all think its all in his head well they dont live this daily ! any one have any advice please im desperate