I took my puppy to the vet, he is a 2 month old pit bull. The told me he had hookworms and ascarids. They gave me a dewormer. A box with 3 packets. I’m to give 1 packet in his food for 3 days. I started on Saturday. Then gave it on Sunday too. I give it around 1 pm. Last nite he pooped out a long thin white worm. Today a while back another. So after the last packet I give him today. How can I tell if he still has worms?