French Bulldog, can't open mouth

[opal]

My Frenchie is having problems opening his mouth more than a 1/2 inch..

Mind you this little guy is usually opening his mouth big and WIDE all the time.
He is just 6 months old and I can't find anything on the net and can't get him into the Veterinarian till Monday.

So if ANYONE has any suggestions of what this might be..

I am open to listening..
I have checked his ears. Still might be something down further that I just can't see though.
Maybe his teeth??

He had hives last week from something we have yet to figure out...
(my husband and I)
Me everyday...
I have never had a dog in 25 years do this so I am stuck..

Anyone...