My Husband (54 Years Old-in Good Physical Condition - Some

My husband (54 years old-in good physical condition - some high blood pressure, common allergies, problems with stomach/reflux) has had hiccups for 48 hours. We cannot come up with any specifics as to why they started except he was particularly busy on Wednesday and tired at the end of the day when they started. He is not having any trouble breathing and they stop when he sleeps and sometimes when he eats but inevitably come back. He takes an over the counter medicine to combat the reflux which sometimes gives him stomach pain. Can you give me any advice?