Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain it seems that he is suffering from Viral infection leading to fever and sore throat
As it is a viral infection it will resolve once the virus will complete its cycle in human body..
It also seems that he is constipated and stomach pain and loss of appetite can be due to it..
As of now you can start with supportive treatment to relieve the symptoms like:
-Gargle with a warm saline solution that is by mixing 1 teaspoon salt in a glass of water and warm it to make a luke warm solution..
-Take a combination of Acetaminophen
-Chew a Vitamin C
-Do steam inhalations..
-Avoid spicy and chilled foods..
-Sip on warm water throughout the day..
-For easing the bowels you can give him stool softener
-Give him salads and green vegetables in diet..
Hopefully the symptoms will resolve within a week and if it worsen consult a General Physician and get evaluated..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.