kitten lethargic wont eat

Question
I think my 7 week old kitten is dying.  I have taken him to the vet 3 times and he says that theres nothing wrong that hes just spoiled.
He was doing very well healthy eating and playing with siblings.  He has had his shots and worming.  He stays inside and drinks from bottle and will eat wet food and drink water from bowl.  He has however had spells that last anywhere from 3 to 7 days where he wont eat (i have to force feed with bottle) he is weak, wont play, sleeps in lap all day, lethargic.  He has done this several times and then he will all of a sudden be fine--eating and playing like nothing is wrong.  
Right now were into about the 3rd day of him not eating, not playing,he is so weak that he can only walk a few steps and he just falls to the side.  His breathing is heavy and labored.and his heartbeat is so fast. We have only been able to get a small amount of liquid in him.  His stool is solid and he is not vomiting. Of all the times this is definitely the worst--he has lost weight.
The vet said that he didnt believe that he has FIP.  At about 4 1/2 wks he was treated for coccidia (Albon)b/c one of his siblings was thot to have it.
All of his brothers and sisters are doing very well they eat alot and play a lot--all the time.
I am so worried.  I am afraid he will not make it thru the night.  I feel so helpless b/c I just dont know what to do.
THank you for your help.

Answer
You should take him to another vet for a second opinion.  If he is not eating and drinking, then he should be given either a SQ fluid treatment or be placed on IVs.

You can syringe him plain gatorade or pedialyte instead of plain water or try KMR kitten milk replacer.

You can try offerring him meat baby food, cottage cheese, plain yogurt, raw liver, boiled burger, chicken breast or tuna to see if any of those interest him.

I would recommend having another stool sample checked to make sure that he is rid of the coccidia as this could be the culprit...normally it is treated with a 10-day course of a sulfa antibiotic.