It happened to my 3 weeks old son too. His stomach passes gas throughout the day and i give her gas drops every now and then when she seems upset about it. I think the noises are normal. If your baby's tummy is hard my mom suggested to hold the baby close to you craddled in your arms and hold her legs up with her knees toward her belly. Kinda curl her in a ball. That helps my baby alot! She usually will pass gas like 5 minutes after holding her like that. hope this helps

Normally, newborn gas is not necessarily a problem or a big concern. This causes no pain or discomfort because it is quickly and easily pushed through the digestive system. However, babies are born with a very immature gut. So the first thirteen weeks of life outside the womb, the newborn digestive system is literally just learning to function. Muscles that support digestion have not developed the proper rhythm (peristalsis) for moving food efficiently through the digestive tract. Furthermore, newborns lack the benevolent bacterial flora (probiotics) that develop over time to aid digestion and complement the work performed by enzymes secreted in the digestive tract. Hence, the reason for digestive issues such as stomach rumbling. See your doctor if it persists