Are the leopard geckos ill?

Question
I have two separate queries about the leopard geckos I am looking after for my teacher. About a year ago, my teacher got a leopard gecko and I have looked after him before over Christmas with no issues. He ate well (small crickets) and loved being handled, he put on weight whilst staying with me and seemed very healthy. About 2 months ago, he was reintroduced with two other leogeckos that he was in a tank with before and who I think are his parents or other family members. Now I am looking after him again for a few weeks and I haven't seen him eat in the week I have had him, he's rarely on or near to the heat rock and is usually in the covered part of the tank. I was given mealworms to feed the three with this time and have bought some crickets as well but he still doesn't seem to be eating. His tail seems quite large still but he seems a lot more lethargic than before. Is there anything I can do to help him? He's the youngest in the tank but has gone from being the sole leogecko to being the youngest of the three. Is this why his behaviour has changed? (I don't know his gender, he's just been given a male name)

The other query I have is about the 'boss' in the tank. She (again I don't know the sex but she has a female name) always goes straight for food and seems to steal it from the others but she's very skinny and has a very slender tail. It's like she's not storing the fat. My teacher said before that she gorges herself and it makes her sick. I removed what looked like partly digested meal worms from the tank last night, which I presume were hers. I've noticed her eye appears to be stuck shut twice now and both times she has managed to lick it and it opens properly again. Just now, whilst she was drinking I saw that the end of her tongue seemed much a darker pink than the rest of it.

I don't get much opportunity to see the geckos when they are at school so I don't know if this is normal behaviour for them. I am concerned as they are not mine about whether they need to be taken to the vet or whether they are normal. Please stop me from panicking! Thank you.

Answer
Hello Charlie,

What is most likely occurring is that he is being dominated.  
Are you positive of the sexes?  It normally is not a good idea to house family members together of the opposite sex due to inbreeding.  He should be separated from the rest, since he is not doing well he will be picked on.  

What are the temperatures in the tank?  Do you use a basking light along with an undertank heater for heating?
Do you have a warm, moist hide/cave for them, also to help aid with shedding?  

Could you get a picture or two of your setup also?  That would help.  
The female sounds like she has worms or parasites if she eats but is not gaining weight or maintaining weight & then getting ill.  I would get a fecal done on her.

The problem with the eye shed is most probably going to be because there is not enough humidity in the tank.  Let me know how they are all doing.  


Tracie