My husband suffers from it, but keeps it under some control by being extremely active - cycling, swimming, climbing, some running. He has problems sleeping at night since his back gets really stiff and painful, he always has to get up and take a pain killer. He is only in pain at night, however, the pain goes away as soon as he starts to move about. He has also had a few bouts of iritis, which needs treatment, so if you have any eye pain or eye redness, go see a doctor immediately and check for iritis. It is a common side problem with the illness.
Go and get checked out, you can have a type of xray to see if the inflammation has caused any fusing in the bones. My husband is still ok in that respect :-)
Good luck and letīs hope this is not your problem after all!