What Causes Infection At The Site Of Lip Piercing?

I have 2 piercings on my lip which have became infected, I took them out, and my lip is really swollen, and I have what looks to be a canker sore on my lip, and a swollen gland in my neck on the side of the piercing, and I haven't eaten in about 2 days, because I'm not hungary, is all of this linked to the infection, or is it something else?