Is this heat patches

Oh no, poor little one, the neck area especially gets so sweaty with all the skin folds, so heat rash there is super common here in Singapore! A few of us tried dabbing a cool damp cloth gently on the patches first to bring the redness down before applying anything, and that seemed to help more than just putting cream straight away. Someone in my mum group mentioned that Calamine lotion worked really well for the red patchy kind specifically, made it less itchy for the baby compared to thicker creams like Aquaphor which can actually trap more heat. Do also swap to loose cotton clothing and keep the neck area as dry and aired out as possible, since the humidity here really makes it linger if the skin stays damp. That said, if the rash is spreading quickly, your baby seems really uncomfortable, or you notice any fever, it's definitely worth getting your PD or a GP to take a proper look just to rule out anything else!