Rashes developing on baby neck

Hi mummy. My baby had that during her 3 weeks old. all I did was wipe her lips and neck with warm water using cotton balls or tissue after feeding. Eventually, it helps a lot. I didn't use any product or any cream. She is now 3 months old.

Yes! My baby also 7 weeks. Should be heat rash. From what i notice, my baby perspires alot, esp around back of neck and neck. And also sometimes milk spills or baby spit milk and didnt wipe properly. Not sure if need to apply anythig.