Behavior in down syndrome/autistic child

My son is 9 years old, born with down syndrome and later diagnosed with autism , he is completely potty trained  since 2years old. Lattely in school he start to vomit, peeing and pooping in his pants  at the same time or as they say This just happened in school, till today where he was uncomfortable going to the airport picking a guest up and suddenly he start to vomit, then peeing ( not in his pants) and pooping.
My question is could this be related to fear or anxiety?

[Sandman2]

   Anxiety certainly could do this.  Have the school keep a record of what is happening just before this happens to him and look for trends.   See if you can find someone to show him how to deal with anxiety.  With his autism, this is very important anyway.
   The school should be able to see signs of this coming on and try to defuse the situation if they know what they are looking for.
    In many ways, this is like a super bad case of stage fright which can be dealt with - if you know how.  Best wishes.