sorry- meant to say tactile defensiveness. i was in a rush earlier. if you search it, there are many activities you can do to help her with this. while it is common, it can lead a child to have many problems due to frustration and discomfort. sensory integration activities can help her overcome it or learn to manage it. in her case it seems to be more than the annoyance it is for so many people- it is genuinely aggitating her.
you can find some activities at
http://www.comeunity.com/disability/sensory_integration/activities-tactile.html
http://www.sensory-processing-disorder.com/tactile-defensiveness.html
Tags hurt trust me ,take them off.and is it not okay she be allowed to wear jeans and sweat pants , I didnt understand if this was a school rule or that you didnt want her to . If it is not a school rule let her wear the pants , it is she who is wearing them.
i'm researching tactile dysfunction myself. i have a student who will not keep his underwear on, refuses to wear a bulky jacket, gets upset by certain pants, etc...
When I was younger I could not stand tags, underwear(I know this sounds stupid but I would have to fold them down, couldnt stand socks they had to be made a certain way)
I might suggest that you google the phrase "sensory integration" or "sensory problems in children" or similar phrases to find more information about this issue. It is not an uncommon problem for many children.
Certainly a sensory issue.
My son's sensory issue results in him not wearing weats in public (too relaxed) - he prefers more of a "business casual" look for out of the house:) He also had issue with tags and most sweaters - I ct off the tags and let him choose sweaters that are "nice to touch"