Cows milk protein in lactose Does anyone know if the casein/whey cows milk protein can be found within processed lactose?

Some background: our 4-month-old baby was given teething granules. She was then presented with a rash, screaming, etc. When we checked the teething granules (called teetha) we found they contain lactose.

However, from reading it appears that lactose intolerance is extremely rare in the UK and cows milk allergy is much more common.
Yes, process lactose could still contain protein from the milk. It's equally likely that the casein could contain lactose. Whey is much more likely to contain lactose since the whey and lactose are in the water when the cheese is made.

It would be extremely rare for a baby to be lactose intolerant since lactose is the major sugar they consume. As the child ages, the ability to digest lactose decreases. I think I heard that 5% of Caucasians adults can still digest lactose. Only a few people develop lactose intolerance.