Hi. It seems that you have an infection of the ear lobe around the site of ear piercing. The presence of pus confirms it. It could have started as an irritation to the metal in the stud or the screw that sits behind the earlobe or during the ear piercing procedure, bacteria from the skin may have entered into the local blood stream around the earring to create an infection. I would recommend that you remove your earring on the side where it is infected to allow healing. The presence of a foreign material such as an earring may not allow natural healing and will allow the infection to spread. You will probably also need a course of oral antibiotics and will need to apply an antibiotic ointment at the site of infection as well. Since there is pus, I would suggest you see an ENT specialist soon so that the infection is stopped from spreading to the cartilage in the ear which can be painful and lead to deformity. If there is a lot of pus then it may need to be drained. One the ear lobe heals, you can wait for a couple of weeks before placing the earring back again.