Does my chin need a x-ray?

My new adult chin has a problematic month. He has got constipation, which was cured after a vet visit. He then got watery eye, which went away by itself in one week. Now he does not drink water or eat pellets from the day before yesterday, but still loves hay. I do notice there is a small red patch on his mouth these two days, probably a wound made by the other chin I have (they are in separate cages but can meet across the bars during playtime). I don't know whether the not drinking thing is related to this injure. Now I'm hand feeding water and a little critical care (because he still eats hay).



I don't really understand the series of the problems. Does he just need some time to adjust to the new environment or these problems are all of one cause? How likely is this due to dental issues? When visiting the vet for constipation, the visual exam of his teeth looks normal.



On one hand, I feel the possibility for him to suffer from teeth is not that big just based on the symptoms, especially considering that he loves hay and chew toys. On the other hand, I'm really confused about his problems and cannot stop thinking about the worst results. X ray is really expensive for me. It's really a splurge but if it is necessary I will do it.



I really hope to get some advice on what's going on with my chin. Is he obviously having dental issues or I can wait and monitor him a little longer to decide? Thank you in advance. It has been such a hard month for me too.