<s>[INST] 10 day old newborn is formula fed and recently changed to a soy based formula due to having diarrhea on a milk-based formula. His stool had just thickened up to the normal pudding consistency. Today, for the first time his stool was really liquidy but I noticed small red strings in his diaper. What could this be from? [/INST] Normally in a breastfed child stools are frequent and on liquid side as amount of solids in milk are less, and intestinal movements are faster. Was he ever breastfed or directly fed with formula milk? Because breast milk is best for infant. In case of your child, soy milk is giving thicker consistency to stools. Check with the prescriber, if you are mixing correct amount of water while preparing milk. For the red strings check his stools if it is - at the beginning are hard or mixed with blood or followed by slight amount of blood. If so check with the doctor for changes in the formula.In the meantime you can apply Vaseline two to three times a day at the anal opening. </s>