I Had a Botox Done on my Jaw Line, but Now when I Am Laughing my Upper Lip Looks Alot Smaller?

It is difficult to answer your question without more details, however, injection of botox around the chin and lips can cause a change in your smile. Often times this is temporary for a few weeks until the muscles adapt to the change.

Botox last for approximately four months, and the region should return to normal at this time. 

It is very difficult to asnwer your question without first knowing the amount injected into your masseters and injection technique. You should consider posting photo's of before and after treatment for better assessment.