Dear Sameskdale, hello
You have not mentioned whether any antibiotcs were prescribed for the cold
infection because antibiotics usually disturb the normal flora of the intestine, which consists of colony of beneficial bacteria. You should give Probiotics after consulting your Paeditrician.
Small children are not able to spit off the sputum during cold and cough
and swallow it. This can result in change in the composition of the stools.
It is advisable that have his stool examined to know if any bacterial / protozoal / infection is present.