My Cat's lip is swollen lip(image included)

My oldest cat Tinkerbell(male) has a really bad lip and me and my mother are getting worried. Please help!

This could be one of many things.  Could be a bug bite, Could be an allergy to plastic or even a specific food.  Do you feed him out of a plastic dish.  Oddly, this is one sign of allergies to plastic feeding dishes.  Could be what's called a "rodent ulcer".    There is really no way for anyone on the internet to diagnose what it is, and, of course, these things always happen on the weekend when it's harder to get in to see the Vet .

Here's another thread about other cats who've had a similar condition, which may set your mind at ease, as none of them had immediate life threatening conditions (that I could tell):  http://www.thecatsite.com/t/264792/cat-has-swollen-lower-lip-pictures-included

I posted a thread in full about this 2 months ago w pictures. My cat had a swollen bottom lip and I predicted from Googling it was Eosinophilic granuloma. I was correct according to a vet visit. As I was milling over a cause low and behold the night prior to the vet visit I discovered my cat had fleas. This is the number one cause. The treatment consisted of just treating the fleas. The swelling went down in 7 days. 

The vet called it pouty lip too. Do watch Tinkerbell's behavior. You want to ensure she is eating well and acting normal otherwise. Many other things can cause a swollen lip but what it usually is is an allergic reaction to something. In our case it was probably flea bites or a rubber band/latex ingestion.

Your Vet may or may not treat the lip w steroids. The best thing to do is find the irritant and eliminate that.