The picture is not very clear so I can't tell exactly if you have a cold sore. But these info should help you out! Cold sores are filled with fluid. if it is a cold sore you should have tingling and some pain. It might ooze over the next few days, and then it will form a crust and heal in about 7 to 10 days. It could have started as a pimple that turned into a cold sore.
pimples around the mouth can turn into cold sores if you try to squeeze them because that causes damage to your skin which can reactive the virus. Once you've had a cold sore, the virus will always lie dormant in the nerve cells in your skin and will emerge under certain conditions such as stress, fever, flu, exposure to the sun or trauma to the skin.
I hope this help! No kissing until it's gone :)