Suggest Treatment For Yellow Perspiration

My 23 year old daughter....healthy and normal weight....just called me in a panic because her white bedsheets and pillow case show yellow wetness in the area where her shoulders and neck and tops of her arms were resting in bed last night. The sheets had just been washed and were fresh before this yellowness appeared. She can also wipe yellow from under her arms/axillary area. She's not ingested food or drink out of her normal routine. Her father has/now undetectable Hep C. She says she's sweating "yellow...." Has never had this occur before....