Sounds exactly like what goes on with the chams I've seen do this. They'll open it if they have to, but they'll close it as soon as they can after that. How long has he been doing it? Are they together?
If he's been keeping it closed for more than a week, I'd take him to the vet and have him make the diagnosis.
And if you have them together, its probably time to seperate them. I'm not sure how old they are, but it sounds like the one is growing at a much faster rate which might suggest that he's been the dominant one, and he's eating all the food and leaving none for the little guy. If this is the case, who knows, it might be a nutritional thing. Whatever the case may be, it sounds like the eye thing, paired with the lip bump definately warrents a vet visit.
Keep us posted on what happens.