Usually what happens is something will get caught in the sheath. You need to take a syringe and steril water or saline and rinse out the inside of the sheath a few times. I have had to do it a couple times to Red. Actually he needs it again.
It also could be pre-ejaculation. Red does that too! did that on my BED!:yikes:
But the constant dripping makes me believe his thingy is irritated and needs a good rinse.
Also do check with the vet as well. Since I am not there and cannot see I am only guessing. Educated guesses but guesses none the less