I also heard that Baytrill stings there mouth so you might want to ask the vet what to mix it with when giving it to him. I had a suggestion of yogurt. When I give my guy Reptaid I inject it into a silk worm directly. This is a huge help. That way you dont have to worry about getting the mouth open.
Here is the definition from Wikepedia... http://en.wikipedia.org/wiki/Mating_plug
A mating plug, also known as a copulation plug, sperm plug, vaginal plug, or sphragis, is gelatinous secretion used in the mating of some species. It is deposited by a male into a female genital tract and later...
Any pictures? It may come off with the next shed. If he is the one in your avatar he might be getting to the size that the part of his body that the shed has not come off yet is not ready. Stay with the shower and mistings though.