Definitely go see a doctor. It could be a sleep disorder, a neurological problem, or an infection.
it if happened all of a sudden it could be some kind of infection, something that mimics Meningitis maybe.
when did it start? do you remember having some flu-like symptoms or gastroenteritis ?
There are many possible causes, unfortunately. It could be thyroid, adrenal, pituitary problem. It could even be constipation. It could be aches and pains you aren't recognizing. If possible, find a reputable doctor, perhaps an osteopath (DO) rather than an MD. A DO tends to look at the whole picture instead of just treating the symptom, so instead of giving you a sleeping pill, they will track down the thing that is throwing your system off and keeping you from sleeping.