Mine struggled terribly with those kinds of situations at that age. He was rigid about routines, frustrated by other kids' failure to adhere to his expectations, and had trouble participating in groups. He has Asperger's Syndrome.
This is not to say yours definitely does; I don't do armchair diagnosis. But "sensory issues" are often a marker of autism spectrum disorders. (And often not; you need a pro to tease this out.) Gifted kids often don't have the conventional language problems or behaviors associated with autism, so they don't get diagnosed right away.
If your gut says something's wrong, I'd pursue it.
I would not trust an OT to make a diagnosis this subtle, nor would I rely on a school psychologist; I'd go to a developmental pediatrician or a neuropsychologist, preferably one with considerable experience in the more subtle end of the autism spectrum. (It took us a few years to get the dx, and we finally got help at the autism center of a children's hospital.)
If they rule everything out, then great, you just have to work on exposure to social settings and let maturity take care of it. If they find something, then you know what you're dealing with and can take positive steps.
Hang in there.
DeeDee
