kitten that wont eat

Question
We just adopted two 5-7 month old kittens from a shelter and took them home on Monday.  It is now Thursday and they haven't eaten much between the two of them.  I've tried about five kinds of food, wet and dry , as well as tuna fish and milk.  The little one is eating less than the bigger one and seems to be having some diarrhea.  I took them both to the vet yesterday and they said they were fine and when i mentioned that they hadn't eaten much the attendant told me it was probably because they were still getting used to their environment.  Could this be the case, or should i worry about the little one, who also has had some goopy eyes.  They have both been using the litter box and drinking water, but not eating much.  
should i take him back to the vet?

thanks for you time

Answer
Hi Jade:  did the vet do an exam on them???  Did they offer you a wormer?  They may have worms and that is why they aren't hungry.
What did the vet do for them??? Did they look at the eyes and the discharge???

Please get back to me.

Thanks
Marie