I still feel its pot luck with DLA forms about whether or not you get it. we have been fortunate to get both dd's on high rate, and some people cant get their head around the fact they get it for ezcema, asthma, vomiting and allergies. they just see it as a bit of dry skin, but it is time consuming, especially now dd2 has started sneaking off to scratch and can cause damage in moments leading to infections.
The thing uhave to remember is to put down the worst days. even if my dd's have a great week, i know the next week could be really bad. i put down every detail, things like changing dd2 clothes when she has been sick, the constant watching to make sure they arent scratching, how often in day we apply creams (dd1 has started doing this for herself now), the foods we have to avoid (well colouring called tartranzine).
If u dont have any success at the appeal then reapply as soon as you can (is there a time limit?). Get your gp/HV involved if possible, get them to fill in the extra bits. My health visitors have been brilliant in helping my dd's get DLA. they mention the fact i cant leave them with people who havent managed ezcema, as they wouldnt know how to calm down my daughters and which creams/bath treatments to use when. so in effect i am on call 24hr a day (tho now my MIL and mum have gotton better at learning these things). Put down if you have to remind your ds to take his meds, or if you have to give them to him.
Just noticed you say you dont know if you have a HV. they should be ones attached to your gp surgery, who should be able to help you with all this.
about the nightime stuff, make sure u really do put everything in. with dd2 if she is sick, then we have to clean her up, get her bedding clean, settle her down, make sure she is well and its just another vomiting episode, all in all can take about an hour, and this can happen several times in a week. add to that reapplying of creams, inhalors if dd1 asthma is playing up. well you get the idea. so if your son is up during the night, or is hard to settle, then make sure you stress how long it takes to get him into bed/stay in bed.
sorry for rambling. hope you get some success.