Yes, it is possible for amoxicillin to cause stomach pain in infants. If your baby is experiencing gas, writhing, and crying while taking the antibiotic, it may be causing discomfort. You can try giving the antibiotic in the middle of feedings to help reduce any discomfort it may be causing. If the situation seems manageable, you can continue to monitor it. However, if other symptoms arise or if you have concerns, it is recommended to consult with a pharmacist for personalized alternatives.