I have a friend that carried a potty training seat with him on every outing until the child was 6, as the boy would literally poo in his pants, after a proper screaming tantrum, where he often kicked and scratched his dad, if the seat wasn't available. Incidentally, he didn't need the seat after 3 at the nursery or in school.
He couldn't run properly at that age either, or use climbing frames in parks, but, having know his dad for many years, I accept that perhaps the boy was not a sports talents but... Everytime we went to the park with them, since the child was 2, the dad will forbide him to run or use climbing frames because he could fall. And in the very few times he had an accident, he was so concerned about getting the child to stop crying that instead of checking him, calming him and asking him to try again, he would tell him that it wasn't his fault, that the place was very very dangerous and that we would never go back to that park. (I know an awesome number of beautiful parks all around Yorkshire due to this promise).
He was a fussy eater, he would only eat fish fingers, sausages (but only those that are sold in Fish &chips shops), petit suis, ice cream and chips. That's all I saw him eating from 3 to 7 yrs old. I have seen his dad removing apples slices or grapes from his hands because "he wouldn't like them", and there were many occassions when we had to leave a restaurant as the child couldn't stop screaming because he couldn't find fish fingers in the menu. Having said that, at school he didn't eat much, but would eat other stuff.
And finally, they wouldn't let the child go down the stairs standing and facing to the front, he needed to go down in all fours and crawl back down the stairs. On that one I couldn't help it and told him that the child would be eaten alive by the other kids if they saw him doing that when he started school at 5. So the last few months before he started school, were spent with dad holding his son hand going down the stairs facing to the front, while the child screamed like mad but after a few weeks (yes, weeks) the crying eased down and eventually he managed on his own.
Don't expect huge changes in a few days, removing such amount of conditioning could take months and months, even years. Yes, you need to take him for a check with the GP just in case there is an underlying problem, but even if he has aspergers, things don't change, you will be expected to take different approaches but still insist in building the independence your child needs.
My son has dyslexia, suspected dyspraxia and AHDH, having a diagnose has only changed one thing: that we know nowadays that we have to work harder in certain things. It has not been a passport to let him be, but something that openned the door to the knowledge of many approaches that could help him cope and flourish even with his disability.