Lagging entities

So Hello.I have been having a issue lately.I wanted to make a armor stand to make a honor pose because i was building a world for my sister.and i went to an animator.i made the pose posted it into minecraft.The command and then something weird happened the sword was floating in the right upper corner.and i broke the armor stand but the sword was still flying and i tried to hit it but it was invincible and i got frustruated and mad so i came to this place to look for a answer to this question.So if you find an answer i really appreciate the help.