It is absolutely normal sometimes. The baby's bowel is still not mature. If there are no loose stools, baby is active, passing urine 6-7 times per day , there is nothing to worry.
Next Steps
1.Can try SYP zinc x 14 days
2. Try Deworming if not done
3. Introduce more solids in diet and reduce milk consumption
4. Babies are explorative in this stage, so they keep on touching unhygienic objects , so try washing their hands frequently.
5. Keep a watch on danger signs- baby being lethargic, refusing feeds, decreased urine, passing watery stools with blood in stools.