Mommas I need your help! Not too long ago I bought my daughter back to school clothes. Upon doing…

Mommas I need your help! Not too long ago I bought my daughter back to school clothes. Upon doing laundry, I noticed that her clothes have stains in them. With whites it shows more. I know for a fact that she hardly dirties her shirts only her pants the most. Yes, I do wash light clothes with light clothes only. We make sure to wash our washing machine at least once a week. What can I do? Now half of her clothes are staining and I wouldn’t want her wearing them to school like that? Any recommendations? Thank you!