Is It Safe To Take Omeprazole Twice A Day?

Is it safe to take omeprazole at 20mg twice a day even if I dont have ulcer. Just hiatal hernia and post nasal drip occasionally that is possibly caused by lpr. Doctor advised me to take it 3mos but i am thinking of stopping by the 6th week since I feel back pains and fatigue, not sure if caused by omeprazole or just too wary of the posts Ive been reading regarding side effects of the drug. Thank you. Hope to hear from you asap.