The stool pattern almost invariably changes when weaning foods are introduced but this change is transient. If it continues it may be because of intolerance to that particular food or due to over feeding. Instead of using ready prepared cereal foods, I would suggest you start with mashed fruit like banana, papaya or apple. Start with small amounts once a day and increase slowly till a full fruit for example, a full banana is accepted at one feed. Then introduce rice cooked until it is very soft like a gruel and dal or milk with it. Slowly introduce different vegetables with the dal and rice to provide different flavours and textures. Introduce two solid feeds after the baby is 6-7 months old. By the time your baby is a year old, you should not need to cook separately for the baby. The baby should be eating the same food as is cooked for the rest of the family provided its not too spicy.