Diaphragmatic muscle spasms, also known as hiccups, are very common. Most people have had them at least once in their life. Causes of long-term diaphragmatic muscle spasms can include mineral and electrolyte imbalances and nerve irregularities.
These can affect the nerves that control your diaphragm muscles (stress, fear and anxiety almost always affect breathing patterns) and cause them to spasm uncontrollably.
Nicotine, especially in chewing gum, is known to cause diaphragmatic muscle stimulation (faster breathing), which can cause the muscles to spasm.
Alcohol is a depressant that slows down your body's central nervous system; this can provoke the diaphragmatic muscles to spasm.
Swallowing air puts pressure on the diaphragm and can cause it to spasm.
Eating a lot will fill your stomach and put pressure on your diaphragm, causing hiccups.