Frequent spitting up on Nan Pro Stage 2 may indicate a sensitive stomach or mild intolerance. Suitable alternatives designed for easier digestion include partially hydrolysed comfort formulas such as Similac Total Comfort, Enfamil Gentlease, or Nan Comfort. If spitting up is the primary issue, an anti-reflux (A.R.) formula may also help. Since your son is 11 months old, he is very close to transitioning to solid foods and whole cow's milk (at 12 months). Please consult your paediatrician before switching formulas to ensure it is safe and meets your child's specific nutritional and growth needs.