Ok 
In the order you answered:
- What the assessors are interested in is the care needs a child has that differentiate him or her from the general population.
As parents, we care a lot about pain, discomfort, etc., but the assessors can't award DLA for pain. The regulations are really crystal clear, that it is the care needs that arise from the condition which qualify an individual for DLA, not the condition itself.
An example, two scenarios (sorry to be boring, but I always do 'compare and contrast' examples):
- John had a car accident which left him paralysed from the waist down. He relies on the use of a wheelchair to mobilise.
Soon after John was told he would be paralysed for life, he started to do a rigourous excercise programme. He strengthened his arm muscles, his upper body muscles and worked to become efficient at propelling his wheelchair.
John uses a banana board to transfer from chair to wheelchair, and has got quite efficient at using it. He lives independently and has an active life.
John would be entitled to HRM, because he has no use of his legs, but NO CARE RATE because he has no additional care needs.
- James had a car accident which left him paralysed from the waist down. He relies on the use of a wheelchair to mobilise.
Soon after James was told he would be paralysed for life, he sank into a deep depression. He couldn't see the point in life now that he couldn't walk, and spent most days in bed. As a result, his muscle tone diminished, and he became weak.
James can mobilise short distances with a wheelchair, but requires full assistance to transfer from chair to wheelchair. Because he has reduced muscle tone, he needs assistance with activities of daily living. He doesn't have the strength to turn over in bed.
James would qualify for HRM, and either Middle Rate or Higher Rate care.
So, same condition, same cause, same circumstance, but the different care needs result in a different award.
What I am getting at, is that unless every statement you make about your DS's pain is followed by a 'this results in this care need' type statement, you may as well be talking about his love of computers. It means nothing (to them).
You need to make sure that you are explicit about what care needs arise from his pain.
a) The time taken to administer pain relief
b) Whether you have to massage his muscles or something else.
c) How the physio programme affects his pain levels
d) How long you are up with him at night because of the pain
e) How often he cannot go to school because of his pain
f) Does he need extra reassurance and encouragement to do activities because he is frightened that he will dislocate or be in pain?
g) Do you have to spend time encouraging him to take pain medicines?
h) Does he tell you when he is in pain, or does he try and hide it because he doesn't want to be 'different'? Do you have to risk assess for him? Do you have to spend time talking through situations to help him decide if he should do something or not?