Muscle Relaxer Cause GERD?

I took a muscle relaxer called cyclobenzaprine (generic Flexeril) for a while to help me sleep at night since I get bad migraines from tense neck and back muscles from a car accident yrs ago. While I was on it I got gastitis, esophagitis, hiatal hernia, and told I had a weak lower Esophageal sphincter. I don't know if the muscle relaxer caused all of this. All of my doctors said it didn't. I was going through tremendous stress at the time as well though that could have led to my digestive issues. Has anyone heard of muscle relaxers causing these digestive problems? Could it weaken my lower esophageal sphinter? Gastritis is listed as a rare side effect?

Thanks