Blackyna, it is definitely possible that it's a reaction to the plant. You might want to switch it out with something known to be benign. I'm a huge fan of Pothos plants...very viney so good for climbing, edible and easy to care for (put them in the cage, ignore).
I really think you need to:
a) make an appointment with a vet,
b) get some sterile saline solution. I would go to the pharmacy counter and tell them you need sterile saline solution with no other ingredients. They can help you find it and know it's the right thing and
c) rinse those eyes out a bit...if there's something under the lids that's causing the problem, that might help flush it out, if it's the result of ingesting something odd, it will probably provide a bit of relief to have it cooled down by the saline solution.
chameleoman, I agree, the picture doesn't look like dehydration at all, but the description of the poop suggests the animal might be a tad dehydrated. Upping the misting is not dangerous and can be very helpful, so I don't think it's amiss as a recommendation.