Watery eyes and drooling is usually an early sign of tooth problems. Of course the "tooth problems" could range from something stuck in-between two teeth, to a chipped tooth, to a cracked tooth to malocclusion.
Not wanting to chew on the harder things, like the lava blocks/stones to the hard food/treats, can often be attributed to tooth and/or gum problems, simply because the gums are to sore/tender to chew on the harder things. If you are using the square lava block, you might want to try the softer pumas stones. If that does not work, I would try pieces (about an inch or two long) of Popsicle sticks dipped in a mix (listed below) ... they are thinner than wood blocks, softer and tasty which should encourage him to chew.
Dip:
1 cup alfalfa hay, stuffed
1/4 cup chinchilla pellets
Place in blender on high speed to pulverize into powder. CAUTION: Do not remove top of blender until all has settled to the bottom of the container. Allow to cool to room temperature (sometimes the blender will actually heat the hay and pellets when pulverizing them).
Add:
1/4 to 1/2 teaspoon Nutri-Cal (found in the cat/dog section of the pet store) It comes in a tube.
1/4 teaspoon papaya enzyme (optional) (can be found in most health foods)
1 teaspoon cold water
Mix these three together and add to hay/pellet powder to make a paste ... a little more water may be added a little bit at a time, until it is the consistency of paste. Dip the end of the Popcycle stick in it and offer the Popcycle stick and all to your chin. Most chins like this and will chew the stick when finished with the dip.
Store in airtight jar in the refrigerator.
Keep fresh hay or hay cubes in the cage constantly. Remove and replace with fresh hay after 24 hours, sooner if it becomes moist.
But, the crusting around the eye could mean many other things also, such as an eye infection or something as simple as irritation due to a slight damage or scratch to the eye.
If you have contacts or know someone who does, there is a very mild eye flush that can be used to soften the crust around the eye. If the crust is on the skin, rather than the eye itself, a tiny bit of Neosporin could be used to soften it and help prevent an additional infection that could be caused if the crust damages the skin. If he will put up with it, a warm moist cloth, held gently in place will also help remove the crust.
As long as he is eating, drinking and pooping normally, you are fairly safe. A vet checkup would be good as soon as it is possible for you to do so.
Jo Ann