did you ask the doctor for advise?
Any stomach discomfort now?
My boy is 9months old, i breastfeed him till 6months plus. now he's on nan2, he eats porridge, cereals, yoghurts, fish and meat, somethings homemade deserts.... but his stools are also mashy type...used to be hard then i change from 4 scoops of formula to 3 scoops and same amount of water then his stools are mashy now... i think its fine for my son.
anyway as long as not runny like diahorrea, should be fine. maybe your baby is not getting enough solid food( if only plain porridge?) to pass out in motion?