Judging from the pics, I doesn't look like there is any blistering or burns near the vent. I think the puffy vent was probably waste building up to be expelled (as it did once the snake was handled.) Therefore, I don't think you need any ointment in the vent, unless you see some red there. As others have stated, make sure you double check the temps one more time, Also, definitely try to prevent the water bowl from spilling, as they could have accelerated the condition. A vet visit is the best idea, but it looks like a burn to me as well.