upper back pain for 18 years

dear scope forum 

i am writing this on my mothers behalf as she doesn't use the internet and any advice or help would be most appreciated.
i shall write my mothers description of how the pain first started and what her pain is like now .

my mother is 74 years old with severe back pain

about 18 years ago my mother was working in a restaurant kitchen cooking food, her boss told her she looked ill  with a blue face and should go home to rest until she felt better  , so she went home to rest . she says she couldn't wake up for 2 days and did not get out of the bed . 
ever since this she has had a pain in her upper back on the left side , she describes the area as behind her heart on her back .

ever since this happened she says she has been short of breath , pain in the back , feeling tired all the time , finds it hard to get out of bed in the morning, feels as though her back is always pulling her back to lie down or sit down .

she has had an xray, mri, ultrsound scans and the doctors have found nothing which gets her down as they can't seem to find the problem . as she is tired all the time the doctors tell her she has chronic fatigue syndrome, but she still has this back pain that is not getting better .

she has always been an active lady and trys to be as active as she can be even now with the pain .

any advice would be greatly appreciated 

thanks very much for reading
brendan