Thanks for your query.
is mostly viral in origin and takes some days to settle.
since baby is not on breast feed and is being fed by bottle,so most important thing is to maintain proper hygiene.
I advise you to give lactobaccilus sached for 2 to 3 days.and watch for his activity,urine output.
there are no symptoms suggesting he is lactose intolerant,like smell and consistency of stools,stool examination can also be done.
In case symptoms do not improve take pediatric consultation.
Your baby will be fine.