I hope I don't sound completely dumb but here goes: My dogs are both unfixed because we plan to breed them. My male, who is neurotic to start with, follows my female around CONSTANTLY, sniffing her butt, licking everywhere she sits. He does this every day, not just when she's in heat or coming into heat. When he does this he does this strange jaw-clicking thing. What exactly is this?
I might mention that these dogs are the first I've had in about 25 years and that one came from the shelter already spayed.
The jaw clacking is him testing her scent to see if she's ready for breeding. Most experienced stud males will only do this when a female is in season. Sounds like your male just isn't knowledgeable yet.
Trey makes a good point. Pyometra can also confuse males and is very dangerous. Doubt that's it, but it's probably worth a look.