Hi all, I’m new to this website but thought I can reach out and maybe find some answers.

I have a 2 1/2 year old Holland lop who I recently discovered has worms.  I’ve had him since he was about 9 weeks old and I bought him from a breeder.  He is a house rabbit and rarely ever goes outside unless I’m brushing him.  He’s also pretty much free roaming during the day but just caged at night.  I also have a 12 year old Maltese who has never had worms or fleas.  So I just don’t know how my bunny got worms?!  About 3 weeks ago while picking Blu up I noticed little white “worms” near his butt area.  I immediately freaked out and took him straight to the vet.  I’m very on top of things when it comes to my animals especially little Blu.  I took a picture of the worms and also brought in a few poop samples for the vet.  The Vet said it looked like tapeworm and gave Blu a first round shot of Droncit and told me to come back in 2 weeks for the second shot.  The Vet did tell me that I would still see the worms because they are dying.  Also the poop sample came back negative of any parasites.  Last Thursday I took Blu for his second shot of Droncit.  Now a week later I’m still seeing these little white worms in his poop.  I’m constantly checking his butt and haven’t seen any but I’m still finding these little white worms in his poop.  I guess you can say its freaking me out.  And I’m wondering if the Vet treated him for the right worm.  After doing some google searching and getting more paranoid from the pictures I’ve seen, I feel that Blu has pinworm instead of tapeworm.  I guess I’m also wondering if Droncit will also treat pinworms.  I know I’m not a vet but I just don’t understand why I’m still seeing these small worms in his poop, or maybe they are still dying.  I just feel bad for my bunny and was hoping someone can guide me into the right directions or should I go back to the vet again?  Any help will be greatly appreciated!!