After thinking it over, our car went back to our regular mechanic to get it diagnosed and fixed. It went in at 10am and my tummy has been upset ever since. After fearing the worst for hours, I heard from his shop around 5pm and are you ready for how much it cost? You really ready?
$59.00 (includes an oil change)
I can't even believe I am going to admit this - but...the gas cap wasn't tight enough. Yup, that's what caused my check engine light to come on.
Lesson learned - make sure you tighten your gas cap!! :)