I would second that his challenges are most likely SPD. There is also a chance he may have food allergies with his problems with foods. I recommend also you both suffering through a skin prick test (especially not pleasant for an SPD individual) checking for food allergies.

I know food allergies seem like they would limit a diet, but if you know what and why foods are bugging him, you can work out techniques and ingredients to diversify his diet better. I have a long list of food allergies, but due to the help of friends and my husband my diet has never been so diverse. As a child, my diet was very limited and my parents had a rough time getting me to try new things. A lot of new things made me sick, so I didn't bother with them again. I stopped telling my family that food didn't make me feel good, since the doctors just claimed I was trying to get attention.

On coordination issues, your son will take longer than the other kids to learn how to do physical things. However, once he figures them out, he could probably teach classes on all the things not to do (since he will have literally tried every possible and impossible option). I know it seems weird to someone who is naturally athletic, but some people just need extra time to figure out thier muscles, balance, and strength. It is especially difficult for someone with SPD whose body seems to be lying to them all the time about their physical reality.