I got a puppy

less than 2 weeks ago from a breeder in Ohio and immediately noticed that her stools were loose, contained mucus, and blood.
She tested positive for 2+ giardia (giardiarsis) which is transmittable to humans. Her vet put her on some meds for 5 days which improved her stools, but the day after it ended her stools went back to its weird state.
My internet research says it's hard to get rid of giardia and that the meds out there are controversial in and of themselves because they kill everything in your stomach.
Has anyone else had this problem? What medications worked and how long did it take to get rid of?
Thank you!