Clothing issues

Hi all. I'm new to the group so sorry if this has been asked before. My 10 year old daughter has a new diagnosis of autism after 7 years of struggling with her behaviour/traits etc. However we are struggling increasingly with clothing issues. Everything is too tight/scratchy etc etc  the biggest issue is underwear And dislikes anything that she has to wear. I've tried all styles of underwear and a range of sizes. Does anyone have any tips or suggestions. Specific seamless underwear are just too expensive. Please help!!