Cold sores are caused by the herpes simplex virus, and they're contagious. Signs and symptoms of cold sores include:
-Small, painful, fluid-filled blisters on a raised, red, painful area of your skin
-Pain or tingling, called the prodrome, often precedes the blisters by one to two days
-Usual duration of seven to 10 days
Cold sores usually appear on your lips. Occasionally, they occur on your nostrils, chin or fingers.
Cold sores generally clear up without treatment in seven to 10 days. If you experience frequent bouts, your doctor may prescribe an antiviral medication to treat cold sores.
Some causes of the symptoms you mention, could be lip biting, lip licking, Vit.B2 deficiency, smoking, overexposure to sun and ill fitting dentures. In extreme cases, this could be due to bacterial or fungal skin infection.
You need to drink plenty of water daily – around 1.5 – 3 litres per day and eat a balanced diet. Do not keep your lips dry; apply lip balm which contains sunscreen – preferably a medicated one.
If you have cracks at the corner of your mouth it indicates B2 deficiency in this case you need to take B2 supplements.
If the symptoms still persist, consult your skin specialist or dermatologist.
Let us know about how you are doing and if you have any other doubts.
Let us know if you need any further information.
Sorry this is a little late, only just saw your message.
I bet it's a mucocoele. I had one of these, and despite information to the contrary, it healed without surgery.