Your concern regarding your child's health is understandable and justified.
Your clinical description fits into a clinical diagnosis of 'MELENA' - meaning: blood in stools secondary to an upper gastrointestinal haemorrhage.
In lay-man terms, this means that your child is having some amount of bleeding into the gut/food-pipe.
The reasons for the same could be multiple. Few of them are:
1. Worm infestation - may times presence of worms in the gut causes bleeding
2. Allergy to cow's milk or animal milk - These children develop an allergic response to the proteins present in the cow's milk or animal milk. Subsequently, they develop small bleeding into the gut
3. Gastric/ dudodenal ulcers - They are unusual in such young children, yet cannot be completely ruled out
4. Other miscellaneous causes
In your child, there is no forthcoming cause that is identifiable based on your description. Hence I suggest that you send the following work up:
1. Stool for occult blood
2. Stool for ova/cyst; Stool for parasitological examination
3. Test for allergy to cow milk protein - IgE levels, Hemoglobin levels, Blood eosinophil counts, etc
4. Stool pH and stool for fat globules
5. Get the child's height, weight measured and check if it is normal for age and sex (with your local pediatrician)
The above tests may give some clue to the underlying diagnosis. Meanwhile, give the child plenty of fluids. Stop all animal milk products temporarily. Watch for any fever or other symptoms that could also give clues to evolution of the disease. If the diagnosis remains unclear or the symptoms persist, then we may need to get an upper GI endoscopy.
Hoping that your child recovers soon from this illness. Take care
Dr. Saptharishi L G