Thanks for writing to HCM!
On reading your question I got to know that your 18 yrs son has asthma
, allergies, and has now developed high grade fever with sore throat
His tonsils appear mouldy and green.
From my clinical experience I can say that he has got tonsil infection, may be because he is so prone to allergy
and is already asthmatic. This infection usually causes high grade fever and related symptoms of sore throat. The green color and mouldy look of tonsils is also due to infection and can be seen in many patients.
What I would do had I been at your place, I would take him to a physician and get him a course of antibiotics, antipyretic
and get his blood test
The doctor may also give him an injectable antibiotic initially, as he is really sick to eat anything, which will make him better fast.
At home, you should ask him to do garages with a spoon of salt in it, four to five times a day ( if he can do it), this will help him feel better.
Hope the answer is helpful
Please ask if you need any more clarification.