6yr old clothing problems

(Georgia)

My oldest daughter is 6. For the past 3 years she has had an issue with jeans and underwear.....ex: fitting too tightly; not in the "right" spot; too low in the back when she sits down and button hurting her belly when sitting down. It has gotten progressively worse. She is very easily upset. For example, if you laugh at her she will burst into tears and leave the room immediately. She just started kindergarten this year. Her homework has be PERFECT or she has a fit and wants to re-do it. Does not like brushing her hair or her teeth. I have to constantly remind her of the task that she is doing....in other words, she is easily distracted. Socks and shoes are another issue. If the socks do not hit her toes just the right way, she becomes very emotional....crying and angry. This will eventually turn into a fit.

She is a very out-going little girl....has many friends at school and does well in school. She is the highest reading class. The teachers have not sent any notes home regarding her behavior. I don't know if this disorder is something she has or not. There were many questions that pertained to her, in many different categories. What should be my next step??