SammyK, until September 18th, I wouldn't have had a clue how you feel. But that was the day Pre-school asked my permission to get an assessment of my DD for 1:1 for the free-play time, because they felt she was 'behind'. Her assessment has taken place, and she needs full 1:1 for all sessions, and is being referred to the Paeds for further assessment.
Everyone has agreed with pre-school, except my family. Who, I have found, can not get their heads around the idea that there is anything 'amiss'. It is SO draining having to say "Yes, I know what you are saying Mum/Dad/Sister, but they don't hand out 12.5 hours 1:1 per week at the drop of a hat for nothing".
"Yes, I can see what you are thinking, but the pre-school sees hundreds of 2.9 year olds over the years, and they know what to expect & feel DD needs intervention."
If only they could see that it would be more reassuring if they said "OK, what can we do to help her", or just accepted the facts, that she does need 1:1, and that is why I am so exhausted trying to look after her, DD2, and being 12 weeks pregnant with DC3.
SammyK, I have ranted myself but what I wanted to say was this:
Your son may grow out of it, he may not, but you will find it easier as time goes on, because you will find ways of dealing with things, and anticipating situations before they occur.
There are some great threads on here about specific ideas. TClanger posted about a sensory bag, on one of the threads. It may be of help? specialchildren.about.com/od/sensorystrategies/a/sensorybag.htm