Jax have a gland in the corner of their mouth on each side called the temporal gland. They commonly get infections there. An abscess can form under the skin of the cheek or around the eye turret and the problem is probably related (there may be connections through a sinus but I don't know for sure). Don't wait on this. The gland will need to be cleaned out, the lumps behind the eyes checked by a vet to see if they are infact abscesses, and may need draining. If the temporal gland isn't terribly damaged you might be able to handle the infection with topical treatment (scrubbing with Betadine) but most likely you'll need a systemic antibiotic as well.