sounds like iron--the house I grew up in had a well,and we would get these reddish deposits from time to time from iron.
The pp is right about mold--sometimes the ickies that can grow in liquid lotions and soaps are pinky red, too. The shampoos, conditioners, lotions etc we all use all start with water, so there is an opportunity for icky things to grow
Most commercial things (i.e. shampoo from a grocery store vs handmade) have enough preservatives to prohibit mold, but if you use things that are either handcrafted, or made without preservatives, youmay have gotten a bad batch?
Most of the time, though you would see any growth right in the bottle, in the lotion, etc itself, not on the walls.