Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern.
As per your complain and presentation of symptoms if the strep test has been negative the white patches on tonsils with fever and headache can be due to Viral
Throat Infection causing
Tonsillitis and fever..
As the antibiotics are efficient in treating only bacterial infection, therefore as there is not bacterial infection antibiotics are not working..
Nothing to worry as viral infections runs its course and is self limiting and will get resolved soon.
For symptomatic relief you can take
Acetaminophen [tylenol] for reducing fever.
A course of antibiotics like
Amoxicillin can also be repeated to prevent secondary bacterial infection.
Do warm saline gargles.
Chew a Vitamin C pellet daily.
Take appropriate rest and do not exert.
Drink plenty of water to prevent
dehydration.
Doing cold sponges over the forehead and body can help in reducing temperature..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.