Changes around or near your eye can be very unsettling. However, your description of a white pimple on the upper eye lid sounds like it could something called a stye, or infection of the small sebaceous glands at the base of the eyelashes. Styes usually appear suddenly and can be very painful. They usually resolve on their own, and the preferred treatment is application of warm compresses to try and naturally "open" the pocket of infection. Manual rupture of a stye is not recommended because of the risk of serious infection in/near the eye. If a stye does not go away on it's own, an eye specialist
can do a small incision and drainage in an office setting.
In your case, the best thing to do is make an appointment with an eye specialist for an exam and any recommended treatment. You may well have a stye and the physician will recommend that you use warm compresses and wait for it to resolve, but it is also good to make sure that there isn't anything else going on with your eye or with your vision. If you wear contacts, it may also be a good idea to switch to glasses until this resolves. An eye specialist can go over all of your questions and help make sure that this issue resolves with no lasting effects on your vision.