My son is 8 years old. Always having cold, sore throat, poor appetite
Generally consistent colds, particularly in younger children, arise from what we call wei qi deficiency - the “wei qi” being the defensive layer of the body in Chinese Medicine terms. If that is the correct diagnosis, often they are given a formula called “Yu Ping Feng Wan” for 3-9 months (generally only during times when they are not sick - during these times you would take something such as yin qiao wan in many cases to clear the active illness quickly and then go back to strengthening the body with yu ping feng wan).
Dietary wise it is often quite helpful to cut sugar and dairy completely from the diet (or as completely as possible).
All that said, there are a host of other diagnoses besides weak wei qi that could lead to frequent colds, so proper diagnosis is critical (see “treating the cause vs. the symptoms” for more on that). You would do best to see a practitioner in your local area.