[joy and bella]

So bella dragged her butt about 2 weeks ago...i thought it was because she had to poop...so i took her outside and she went....than today she dragged her butt again...but when i took her outside she didnt poop...we were out there for 25 min and she didnt go......i asked a friend...and they said she could have worms...and that when dogs drag their butt thats what it means. i thought it meant they had to go the bathroom.....can anyone offer some advice?? if she does have worms how serious is it? can i wait till tomorrow to take her to the vet? could it be potentially harmful if she has had them for two weeks?? thanks everyone