Hello Tracet and welcome to the forum,
Keratoconus often seems to appear around the time of puberty, so it's common for it to be diagnosed in the teens. And usually one eye is more affected than the other, so making sense of slightly different images from the two eyes can often lead to headaches and squinting. People with KC do often have the allergies you mention, but there are also lots of us who don't have any allergies. Glasses often don't help very much because they often can't correct the irregular astigmatism that's a feature of KC. So your son may be reluctant to wear his glasses because they don't improve his vision very much. Progression in KC is very variable - it can sometimes have a 'spurt' and then slow down. Whether your son wears his glasses or not won't have any effect on that, so I'd just leave him to do what's comfortable for him. The hospital may well suggest rigid contact lenses for him instead - they usually do improve the vision a lot because they correct the astigmatism much better.
Is the deterioration in his vision affecting his school work? If so, there's a leaflet you can download from the home page of this site 'Supporting Students with KC' which you can give to his teachers
www.keratoconus-group.org.uk/sitev3/publications.html It's always scary to get a diagnosis of a condition that no-one has ever heard of, but options for keratoconus are improving all the time with lots of different contact lenses to choose from. And if KC does carry on progressing, there's the possibility of collagen cross-linking (CXL) to halt the progression (though there aren't many hospitals that offer it on the NHS at the moment).
I know you say you've been bombarded with information, but if you'd like our information booklet on the condition and the DVD of our 2009 conference which covered all the current options for KC, just e-mail your postal address to
anne@keratoconus-group.org.uk and I'll put them in the post to you.
I hope you'll get the hospital appt through soon and that will help to put your mind at rest.
Anne