My dog has whipworms been to the vet got him some meds, he was eating till Saturday then I only got him to once that day,Sunday he ate just 3 TBS of dog food (wet,IAMs) now he turns his head when we feed him. He drinks just a little of water when I give him some. HELP.

I think you should touch base with your vet and let them know this.
Needless to say, if he is refusing food then he still doesn't feel well.
Dewormers are pretty safe overall, so I doubt that the medication is making him feel poorly.
Was he put on any other medications? If so it could be that they are upsetting his stomach.
There is generally a repeat treatment, with whipworms sometimes three.
How far along are you into the treatment?