<s>[INST] hello, my 3 month olds stool is a combination of mustard watery stool and dark gray firmer stool.  he is on both formula and breast milk (breast milk mainly).  nothing has changed regarding his diet.  this is the first time this has happened. is this normal or cause for concern? [/INST] Reclothe transient change in pattern and frequency of stool is normal in early infancy. I won't get worried if the baby is active, playful,accepting feeds well and passing urine at least 4-6 times a day. No treatment is needed as the stool pattern will get normal itself, within few days. I would suggest you to maintain proper hygiene and to avoid the use of feeding bottle for top feeding. The use of feeding bottle may cause nipple confusion and the baby might hurt your nipple leading to soreness. Continue the feeds and if the baby is getting lethargic/irritable or there is decrease in urinary frequency consult your physician. </s>