Thanks for your query.
Your baby is having diarrhea
which could be due to increased gastrocolic reflex or viral in nature
This is good that baby is active,accepting feeds normally and is on breast feeding.
Relax,weight is normal as per age,baby doubles birth weight
by 5 months of age.
Continue with zinc and oral rehydration solution.
Also give probiotic
like lactobaccilus for 2 to 3 days.
Mother should avoid gas forming food items in her diet.
If symptoms persist get re evaluated by pediatrician
Wishing your baby good health.