HI...I congratulate you on providing me a detailed hjistory. it was very useful. By what you quote I put forth 2 possibilities -
1. Hirschsprungs Disease. - as you said it needs
biopsy.
2. Cow's milk
protein allergy.
I was expecting that there should have been a history of cow's milk and formula feed (this too contains cow's milk protein) given to the baby. I feel that your baby is having cow's milk protein allergy. Unusually babies grow out of this sort of allergy by 1 year of age.
My suggestions for you -
1. Mother should go off cow's milk protein completely. This means that you should avoid consumption of anything and everything related to cow's milk - like - milk/ curds/ ghee/ butter milk/ chocolates/ biscuits/ ice creams etc. Even while buying commercial food products, you need to see the ingredients and if they contain milk - do not consume them.
2. Feed you baby only exclusive breast feeds till 6 months of age and then start rice based feeds.
3. If this is followed scrupulously - the baby will stop having
diarrhoea in another 3-4 days and then start gaining weight too.
4. If you feel your feeds alone are inadequate for the baby, then Zerolac is the only option till 6 months age.
I request you to keep me posted about the recovery of the baby and follow of the case.
Regards – Dr. Sumanth