Children need lactose for proper brain development, another misconception caused by industry. They'll ruin our kids one way or another! True lactose intolerance cannot develop until age 4.
It can take 12 weeks for all dairy to leave your system. So don't be too quick to rule out the dairy protein.
This is a sensitive subject, and I am not trying to upset you. Unfortunately, there are too many misconceptions out there about infant feeding.
Chamomilla is for irritable children. Perhaps he had a proving.
Goats milk would probably be your best bet if you don't want to relactate. The fresher the better.
Colicky babies are no fun. You are doing a wonderful job in asking questions and seeking the best for your son.