Galaxy S4 sending blank and phantom texts

I recently just switched over to a Galaxy S4 and I love it! But recently it's been sending blank texts. And it's also been taking texts from a conversation with one person, and sending those texts to another person. It wasn't a group message or anything. 

So far my phone has only been sending these texts to one person. I'd really like to stop it now before it starts sending blank messages and mixing up conversations with all of my contacts! Help! 

Thanks!