whats wrong with my guinea pig!?

  i had two guinea pigs, they are about 5-6 years old, a few months ago, one of them died, they had lived together for pretty much all their life. i still dont know how my other one died, maybe from old age ? but now i think my other guinea pig is sick or something, and is not going to make it, he hasnt been eating or drinking, hes been really skinny all his life, but hes evn more skinny now, and he doesnt walk around much , and his eyes are extremely watery, and he just layed down for a few seconds breathing really heavily, he has been like this for about 2 days maybe. whats wrong with him!? what should i do!? thankyou for answears (=
As you can tell, he is obviously ill, so the best thing you can do is to take him to the vet. Not eating or drinking is very serious in a guinea pig - don't wait any longer - take him to the vet, or he definitely won't make it. Mash up some of his food pellets in warm water and syringe feed this to him every few hours to keep him going until he sees the vet, but get him there as urgently as you can. Guinea pigs go into irreversible liver failure after 16 hours without food.
You take him to a exotic vet asap, I cant believe you need to be told to do so. You guinea pig is close to death so if you do not get him there asap you will not have him either.
I cannot believe you have left it! You should have taken him to the vets as soon as possible as he is clearly in a very bad way. You cannot leave this. He is in a lot of pain and discomfort.
If your guinea pig isn't drinking about a cup of water each day then regardless of how they look they should be taken to a vet
go to a vet asap. trust me , even a normal vet would no best
he cold just be really depressed my piggie did that when his bestie dies after a dog attacked her she was a rabbit but we just kept on holding him and he got better but I think you should take him to the vet it sound seriouse
take him to a vet, it sounds silly but they'll be able to tell you whats wrong with him