Hm, it is hard to say without seeing it (probably even with seeing it over the internet). I cant imagine a cup would cause that. Were you drinking hot liquids from it? Could you have burned yourself at one point? Have you kissed anyone new? :>)) Herpes simplex one is contagious and you can get it from that kind of contact. If you didn't burn yourself and this spot remains, your best bet is to get it checked out by a doctor. It's not a pimple or trapped hair follicle or anything like that?
A swollen lip is the result of either inflammation or fluid build-up in the tissue of the lip. Discovering the cause of your swollen lip may take some detective work. It could be an allergic reaction to something. If you take an NSAID and Benadryl and it gets better you can typically correlate this with an allergic reaction. Could you have somehow injured you lip with your new Yeti and not realized it? Other causes could be cellulitis. Pimples on or near the lips may cause some temporary lip swelling. Severe swelling can occur if you have cystic acne. This serious type of acne can cause large boil-like lesions anywhere on the body. Cold sores, herpes infections, and coxsackievirus blisters around the mouth can also cause lips to swell. These changes are symptoms of a virus and may appear overnight, even though the virus has been present in your body for a much longer time. I would try some Advil and Benadryl first and see if that helps. I wish you all the best!
Hello~I hope this condition has cleared up, but if not, I suggest seeing a dentist, they are probably more versed in handling issues like this than a regular PCP.