My almost 7 months old baby's head is hot. he is drooling excessively and hi appetite is reduced but he breastfeeds very well. what could be the issue?

Hard to know: The infant head is ~ 1/5 of their body surface & where they release heat readily in normal body temperature control.Drooling is often just because the don't have the social taboo not to. I don't use these symptoms as a sign of anything specific.

Sun Safety: Keep your baby away from direct sun exposure during the day. He can wear a hat, sunscreen lotion. Keep him well hydrated with fluids including sterile water. Please ensure that he is having wet diapers at least every 6 hours and a visit to your pediatrician is suggested.