Brief answer:Oral Thrush secondary to viral infection.. Hi.. Thanks for the query.. As per your complain it looks like viral infection and can be probably Mono but can be confirmed only after a proper clinical examination and blood tests.. White substance all over the mouth seems to be due to oral thrush that is a fungal infection caused by Candida Albicans fungi.. It is an opportunistic infection caused when there is reduced immunity or other causes like intake of antibiotics and steroids, dry mouth etc.. So my suggestion is to consult an Oral Physician or a general physician and get evaluated and a thorough clinical evaluation and investigation like blood test as well as microscopy of the scrapings from the mouth can help in diagnosis and treatment can be done accordingly.. 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 and Ibuprofen.. -Chew a Vitamin C pellet daily.. -Do steam inhalations.. -Avoid spicy and chilled foods.. -Sip on warm water throughout the day.. For thrush in mouth Physician can advise you to take antifungal medicines like Fluconazole or Itraconazole orally.. Nystatin mouthwash and clotrimazole lozenges can be advised.. Taking more of probiotics like Yoghurt and Garlic will help in faster clearing of fungus.. Drink plenty of water to prevent Dry mouth that is common in Thrush and chemotherapeutic agents intake.. Hope this helps.. Regards.