hi there, GF is diagnosed by a definative blood test which usually takes about 24 hours to process. Although the Epstein-Barr virus (GFever) is not very contagious, it spreads from person to person in saliva, which is why it is sometimes called the kissing disease. It also spreads through coughing and sneezing and probably in tiny droplets in the air when people talk. Tonsillitis is contagious because of the nasal fluids and drops coming out of the mouth, while sneezing and coughing are infectious enough to spread the disease to other persons quickly. If it is tonsillitis then the antibiotics should work~ sounds like your gp thinks this diagnosis more probable. Its alot easier to treat. GF can last for months and depending on how intense it is depends on how long you feel symptomatic. I have had GF and it lasted for 1 year and i was so lethargic and ill it was hard to get up and running, on the good side you usually only contract GF once in your life if at all. I wish you well and hope the tablets work :)