Does he seem to be in any pain or discomfort from this? If yes -take him to the vet, just in case there is some swelling or inflammation.
If not, then maybe wait a little while longer because this will probably go back to normal gradually. But obviously, if it doesn't in a few hours, go get him checked out.
I am guessing your dog isn't fixed? He's got excited -probably got the scent of a female in heat or something. Maybe even the scent has been trodden into your house on shoes etc. You won't smell it, and that won't do your house any harm....but it might be the reason why he remains so excited!
If you find him continuously sniffing a certain area....say beside your gate, or just outside your property, that might be the place where the scent has lingered. If you see that happening, you could scrub that area with hot water and disinfectant which will kill the scent. And cool his ardor!!
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