hello karina, these symptoms may be indicative of lactose intolerance secondary to chronic or persistent diarrhea that may be secondary to any infection. some other causes like various malabsorption syndromes can also lead to these symptoms. generally diarrhea associated with mucous or blood or both may be indicative of some pathogenic bacterial infection that may require some antibiotic for treatment. lactose intolerance may be caused in these children secondary to such infections and they take some time to recover once the infection is treated. for this you should get a stool routine with pH and stool culture done for diagnosis. it the diarrhoea is not treated well in time it may lead to malnutrition in your child that may affect overall development. so my advice would be to take your child to a pediatrician and discuss these possibilities with him. he may also advice some other test as relevant for diagnosis and prescribe the drugs depending on the report. meanwhile you should give your child nutritious diet if possible free of sugar, and maintain adequate hydration by giving fluids. you can also give zinc preparations available at pharmacy that will help a bit an diarrhea. hope my advice is helpful for you wish rapid recovery of your child regards Dr. Amit Kumar