M.,
I agree with other posts that have been made. I have a 9 year old step son that has Sensory Integration Dysfunction. He was diagnosed with this in 2000 and we have worked hard to help him deal with the different sensory issues he has. Some are/were similar to the ones that you describe but also noises, textures of certain foods and language. If you find that he gets overly aggitated in a busy or crowded store, maybe he won't eat certain foods or gags when trying something with a new texture.
This is definately something that can be worked on and over come. I have worked direcly with my step son (he lives with my husband and I) and he can now touch just about anything (sometimes he will stop for a moment but then try again), he no longer gags on mashed potatoes and it has now become one of his favorite foods and he loves to be hugged and kissed, which early on, we could not touch him without him screaming
If you son displays any of the other things that I mentioned, a good book to read while you wait for an appointment with a specialist (if this is the route you choose) is The Out of Sync Child. Sorry, but I don't know the author's name. This book helped us immensely. We also used various Autism books to help with other situations.
I do recommend seeing a neurologist - we had a great one that still sees my step son once per year even though he is no longer in regular practice. He is amazed at the progress we have made in such a short time.
Although this is my first time posting on here - feel free to contact me (if you can) and I can talk more about this with you and how we handled the emotional ups and downs (there is truely a roller coaster with the highs and lows of this)
Good Luck - B.