Can guinea pigs die from depression?

i had rescued two male guinea pigs about 6 months ago (their age is unknown). i had to separate them soon after getting them as one was aggressive toward the other to the point of hurting to less dominate (i had to do this even after moving them into a very large c&c cage). i had them near each other so that they could squeak to each other although they never really did. recently one of them stopped drinking and then eating and would sit hunched over in the conner. so i took him to the vet who found nothing medically wrong with him so i continued to force feed water and critical care however he died soon after the vet visit. could he have died from depression? any ideas what could have caused him to loose interest in living?