Sour sensation and tension in jaw

So for the past three days I have had some jaw pain, mostly just tension that increases when I'm stressed, or when I chew a lot. It's the most concentrated under my ears. I assumed it was just from clenching my jaw without realizing it, but the really weird part is that I have this sour sensation in my cheeks, like I'm sucking on a lemon. It's rather uncomfortable. It doesn't go away really, and eating anything that is sour or acidic makes it even worse. I also have been told that my face looks slightly swollen around my jaw bone. (Aka I look like a chipmunk). Any ideas?

Could be mumps.  You can get them even if you've been immunized.

or it can be a simple ear/jaw infection.  Go to your PCP.  Most likely it's an inner infection.   Easily treated.   I'm actually prone to them, and I'm 25.  So go to your PCP and have them take a look.

I felt the exact same when I got mumps. You can be feeling like that for up to 2weeks until it actually flares up. Crap thing is that there is nothing you can do about it! No kissing (because you can pass it to someone else up to 10days before you flare up) and lots of nurofen and paracetamol.

The worst 2/3weeks ever for me. I HATED mumps. So painful and I cried everytime I looked in the mirror, haha.

I feel the same way when my TMJ is acting up.  I have cracked my jaw bone at least four times due to TMJ.  Go to your dentist and have him/her X-ray your jaw.  If it is TMJ they will make you something like a retainer to sleep with.  It helps with jaw stress a lot.