I think my one 12 week old BRs has gape worm. I have seen her shake her head rapidly and then "open her mouth wide. I read a post that ivermecin will kill the worms. I bought Noromectin a generic brand of Ivermectin. It is injectable 1% solution. What dosage should I use for a 12 week old, and should I deworm them both (I only have two chickens). What is the best (easiest) way to administer it?