I'm not sure what V&E is, either.
The rooster needs some TLC, as it sounds like he was pretty sick. You should give him some high protein snacks, such as boiled eggs and yogurt. This will help his intestinal track regain some beneficial bacteria. You may also want to consider some vitamins for him.
The Piperazien needs to be administered again in 30 days. It doesn't kill roundworms, just paralyzes them & allows the chicken to expel the worms in their fecal matter. Any eggs that are still affixed to the intestinal wall will hatch & be big enough to expell with the second round of worming at 30 days.
Remember that you can't/shouldn't eat the eggs during the withdrawal period. Depending upon the source, the withdrawal period can vary from "3 eggs" to 10-17 days. You'll have to decide how long you want to wait before you start eating the eggs again.