I'm going with prolapse here. I've seen many a hemipene and it's generally a lot pinker than that, at least from what I've seen. If i recall correctly, the dark red color is actually the veins that run through the colon/intestine (which is what is hanging out during a prolapse). Now, I know this sounds weird, but I have encountered this with humans in my line of work. The best course of action, with humans, is actually using olive oil and not lube, as the lube is actually part of what can cause the prolapse in the first place. Basically, the lube allowed a somewhat of a suction effect on humans.
If you use olive oil, it keeps it moist, it doesn't hurt the exposed organs with chemicals in the lube and once the doc gets everything tucked back up, the body has an easier time either absorbing or expelling the oil rather than the lube. Now, some people who prolapse their anus can actually ease it back in by relaxing and prodding the muscle tissue over and over again. This isn't recommended though, since many times it can introduce infection to the anus. Then again, this is all I know FOR HUMANS and not for chameleons.
So unless you are into prolapsing your anus, I agree with the take to vet idea, but I recommend using oil for lube over KY jelly, just because I, personally, don't know the effect KY Jelly chemicals will have on a chameleon.