Poor guy. I don't know if it is normal or not but I was like that as a kid and my one son was like that, too. OK, we are both sort of still like that but less so as we get older.
When I was younger, I couldn't stand to wear anything tight, itchy, scratchy, and everything was magnified, like if one shoe buckle was more snug than the other. My mother's response was "you have to suffer to be beautiful" so she didn't indulge me but I can still feel the discomfort of those tight ponytails and stiff petticoats.
My son is picky about his clothes so I let him choose what to wear and if he wants to wear the same pants 3 days in a row and I can't smell him coming, he can do that. He has to be comfortable. When he finds a pair of pants he likes, I go back to the store and buy several more just like it, in different colors if possible, if not, he gets to wear the same color like a uniform. He doesn't care. Neither do I.
Since your son is mellow about other things, I'd let him have some control over his clothing. Perhaps he can try on and set out his school clothes the night before to make sure everything is clean and fits. Wash more often. Replace his shoe laces with a different length so they loop just right without having to triple knot them. Get some shoe inserts and pads, or different socks to see if that keeps his foot from slipping around inside.
If you find some type of therapy that helps your son deal with his clothing issues, that's great. If not, he may just be a sensitive, kinesthetic type of person, and will have to accept it and adapt as possible. But for now, the less he has to think about his clothing discomfort, the more he can concentrate on his school work so I'd start with some practical adjustments to his clothing and see how that works.