They are with out a doubt worms. I would take her to the vet to get wormed. Because if you just leave them eventually they will make her sick and could even kill her. She is dragging her butt because the worms are trying to come out of it and its her way of scratching it.
My Dog Drags Her Behind On Carpet And Little White Rice Looking Worms Or Something Left Behind. They Could Be Worms?
Yes it sounds like she has worms, what you are seeing are probably eggs,get some advocate spot on from the vet, you apply this to the neck every month and it keeps your pet parasite free. Hope this helps x