What Causes Lower Abdominal Pain, Diarrhea And Constipation While Having Acid Reflux?

Hi had a really bad painin my chest and in lower jaw at same time this has maybe happened 3 or 4 times in as many years, went to had a ecg and was given the all clear for my heart, my go then said it was acid reflux and prescribed me with omeprazole which I have been taking for the last 3 months. I thought it was a little odd to be prescribed a daily medication for something that occurred once a year but have done as the Dr prescribed. I have been suffering side effects of extreme flatulance and over the last 2wks have had serious lower abdominal pain, acute diarrhoea some constipation and bloating could this be because of a lack of acid and now a possible infection