my dog has worms and we used the safeguard stuff and it didnt work at all so how well does the d-wormer stuff work?

on the shelf.. does anyone know why and what else can i use to treat them?

the pills are called d-worms n i got them from petco. n imgoing to get the shots at petco

Its only 4 weeks old and i some symptoms that he has is a bloated belly and he eats a lot and even when I try to help him poop he wont hes only pooped twice in 2 days, i heard these are some of the symptoms to round worms so i was wondering if i could give him the medicine because of his age?