a month ago i rescued a 6 month old rabbit, I know nothing about the previous owner, we found him in the bush and wasn't microchipped so decided to take him in. (he's albino and I think he is a mini rex, he's my first rabbit and i am still learning!) 2 weeks ago he started to close his left eye. its mostly when he's relaxed/eating, but he can open it completely when he needs to. otherwise it looks completely fine, theres no redness or discharge coming from it. he eats normal and is active! i've taken him to vet and they couldnt find anything wrong. is there anything else this could be?