Hello, you had mentioned about swollen lip and mouth ulcers, which you had noticed for the last 3-4 days, and it is painless. Mouth sores can be painful and annoying. They appear inside the mouth, lips, cheek, tongue, palate and gums. These sores can be caused by bacteria, fungal or viral or even cancer, other causes are irritations from dentures, loose orthodontic wires, sharp edge of a broken tooth or filling, extreme sensitivity to ingredients in toothpastes or mouth rinses, side effects of medication, certain specific skin, oral or systemic diseases. The most common sores are canker sores, cold sores, leukoplakia and candidiasis or thrush. Some people experience painless spots in the mouth. Most of them are harmless and disappear. But some can be serious and need the attention of a dentist or physician. Oral causes to start with it will be painless but can be deadly. That is why regular dental checkups are important. If the sores do not heal within 2 weeks, get yourself examined by the dentist.
Canker sores: Fatigue, emotional stress, genetics play a role, cause is not known, not contagious or precancerous, no permanent cure but only treatment is to relieve the pain. Avoid hot, spicy or acidic foods. Topical application will give temporary relief, may respond to corticosteroids. But most of them heal spontaneously in 7-10 days.
Cold sores: They are painful blisters, caused by herpes virus Type 1 or Type 2 and contagious. When once a person is infected with virus, it can remain inactive in the body. In some people this virus activates periodically. No cure for these viral infections. Topical or systemic antiviral drugs can be prescribed, but they are ineffective after the 3-4 days of the blister formation and not recommended in otherwise healthy patients.
Leukoplakia and Erythroplakia:are precancerous, but to be ruled out by the dentist or physician. Usually associated with smoking or alcohol.
Lichen Planus: cause is genetic also to a chronic immune system reaction, not contagious, does not pose of becoming cancer. No cure, treatment is for discomfort of pain. Diagnosis is by biopsy and clinical characteristics.
Candidiasis: is a fungal infection. Usually associated with diabetes and AIDS or also who wear dentures (old people). May be seen after antibiotics treatment, can be painful and may cause bad breath and difficulty in tasting or swallowing. Treatment depends on the cause. Good oral hygiene is essential.
Oral Cancer: are usually associated with smoking (70%) or alcoholic beverages. To begin with they are small and painless and should be checked by the dentist as early as possible. Early diagnosis and treatment greatly increase the chances of survival. In your case, you need not be panicky right now, you have been advised to take Flucloxacillin for a couple of days and then go for a check-up with your physician, and at the same time get yourself checked by the dentist as well.