Cold sores, as you may know, are due to infection of the involved skin areas by the herpes virus. Infection with this virus is very common and, in fact, once you are infected the virus never entirely goes away. Rather it goes 'into hiding' from time to time, only to reactivate when you get sick or stressed. This is why cold sores crop up from time to time.
When you do have an active cold sore, it is very contagious, as the virus is shed from the surface of the open sore. For this reason it is very important to be careful when you have an active cold sore. You can spread the infection to other people by sharing dishes or by kissing (or other activities that expose the other person to your saliva). Similarly, you have to be careful about spreading the virus to other parts of your body; in particular, the risk of spreading the virus to your eyes if you touch the cold sore and then touch your eyes is significant.
I suggest that you visit your primary care doctor
to talk about this issue. There are several medications that can be used to help clear up cold sores more quickly and also decrease the frequency of the flare ups and the contagious periods.