I started having hiccups last night, and they went away after about 30 minutes. I woke up and had them for about 30 minutes again. They went away and I got them about 3 hours later for about an hour. They stopped so I took a nap but I had chest pains the whole time. I woke up and I have them again and it is going on an hour and a half.

Summarized question: What causes recurrent hiccups?