I have a hiatal hernia and take omeprazole. I am having awful chest and back pain/pressure with fullness and belching. Should I call my pcp?

YES. You should definitely notify your doctor of these symptoms. One form of hiatal hernia allows the stomach to enter the chest alongside the esophagus (paraesophageal.) some patient so afflicted may twist their stomach and lead to serious consequences. So, please, notify your doctor. In the meantime, eat smaller meals, avoid carbonation, and don't recline soon after eating.
At least. Yes, but your pcp may not put the symptoms together with the hiatal hernia. These symptoms are typical of large hiatal hernias, but also make sure it's not your heart, or esophageal spasm. They will know the tests for the heart. Need an upper GI contrast study for the hernia . Maybe esophageal manometry to check for spasm. General surgeon w/ experience w/ hiatal hernia if that's it.