Hi S.
I agree that firstly comfort your child.
I disagree that it is a phase, it may not pass. His personality is shining through, and he may well not get over this. He may just like we are -all different, He has his own views of personal space, and what people make him feel un/comfortable.
Yes, use your words to help him know how to describe his situation, and feelings so that he know what to say when he grows up. Show him and model for him appropriate social behavior so that he can get out to his own space and feel comfortable (eg,Please excuse me).
You can only respect your son's feelings, and you can teach him to respect his feelings too, and make choices about what to do with them. However you can't make him into something that he isn't. He may never like loud people, but you can teach him how to deal with his feelings about that .
Regards
P.
(mom to a very very shy child who I have spent much time with to be be more socially aware)