I really feel you on this, it can be so worrying when you suddenly notice something on your baby's skin. White spots on the neck could be a few different things, not just heat rash, so it is hard to say for sure without a proper look. It might be good to bring your little one to see the PD just to be safe, so you can get a clear answer and some peace of mind. You are doing the right thing by checking early, mama.