I wouldn't worry too much if she is just dropping percentiles, but it sounds like she is also actually dropping weight. While this could just be that she is more active, I would still want to thoroughly look into it to be sure. One thing you could check are her Carnitine levels. My son dropped a pound between 6 and 9 mos checkups and it turned out his Carnitine levels were low. He needed to take an oral supplement for awhile and eventually outgrew it (which some do and some don't, but even if they don't it's just a matter of taking a supplement.) I know weight loss can be caused by a lot of things (and it sounds like you've got a good guess with intestinal parasites) and this may not help at all, but just one more thing to add to the list of things to check. (By the way it is a simple blood draw that checks this, so both the diagnosis and "cure" are relatively simple.) I would voice my concern to the dr. and if the the dr. thinks its okay to wait until 9 mos, then watch, but don't worry. Of course, if you are concerned, take her in. Better to be the overprotective mom who is in the dr.'s office unnecessarily than to have missed something crucial! Good luck!