Infant With White Mucus In Stools, Started With Baby Rice. Cause For The Mucus?

HI my baby is just over 4months old and i have started giving her a little baby rice mixed with her formular milk, 2-3spoons at a time, once a day on a morning about 45mins after her first bottle. I think shes been teething , she has been showing the typical signs. But for last 2-3 days she has been having stringy white mucus in her stools . She has bowel movements once a day, they are mustardy yellow in colour and at a pastey consistency. Shes well in her self, normal appetite etc. Before this stringy white mucus came up I believe she was a little unwell with a litttle diarrhoea Only thing thats really concerning me is the white mucus in her stools. I haven t caused a problem with her kidneys have i?; by starting her with baby rice. thank you