Puppies generally get worms thru their mother. One dose of worm medicine is all that is needed for this when they are weined. Sounds like your little 12 week old puppy has already had more medication than she should have at this tender age.
http://www.wholisticanimal.com/petvaccinations.html http://www.chron.com/cs/CDA/story.hts/front/1377004