Typically and in the majority of cases, a hiatal hernia remains
asymptomatic, and patients report no complaints and lead a normal life without
even realizing they have that defect. Larger hernias and para-esophageal
hernias, however, manifest themselves more clearly and are more prone to producing
complications. Hiatal hernia is dubbed as the "great mimic" because symptoms
it entails can imitate those of many other conditions. For example, dull chest
pains (from acid reflux), shortness of breath (from diaphragmatic or, in severe
cases, lung obstruction), and heart palpitations (from vagus nerve irritation –
the vagus nerve control a number of involuntary functions like heart beating,
sweating etc.) can all be encountered in a patient with a hiatal hernia.
Typical symptoms are those generally associated with GERD (gastroesophageal
reflux disease), as well as frequent vomiting if the hernia is severe enough
(the bulging segment above the diaphragm is large enough to cause loss of
control over the backward motion of stomach content).

I do not know the type or extent of your hernia, but as I
have explained above it may very well be causing the symptoms you are
describing. You should follow up with your treating physician on the matter.