I am unable to message my bot back-and-forth to test it. Anytime I send a message, the red “error sending message” box comes up on the bottoms of the screen. Has anyone else experienced this? Is this user error on my part? 

Does this problem persist if you log out and log back in again?

Yes. I wonder what would prevent me from testing my chat bot?

If you open your web browser console, do you see any errors? https://appuals.com/open-browser-console/

It was my browser. I switched to Microsoft edge and it worked. I wish I could use Firefox,