I'm 33 and averagely active, 4 days ago I woke up in my bed after a bad night’s sleep of tossing and turning. I think I was in an awkward position and my arm was underneath me, and as soon as I moved I felt something give in my upper arm. (it felt like). It turned out that the joint connecting my arm to my shoulder has completely fallen out of place.
It was real agony for a few minutes and then subsided to a dull throb as I lay still. I assumed I had pulled an arm muscle, so for a few hours I lay there, waiting for my arm to recover, and trying to make small movements in order to get out of bed. The pain was too much in the end and I had to be brought to hospital to have it relocated. They gave me morphine and put me under, and when I woke up my shoulder was back in place and the relief of having the excruciating pain removed was overwhelming.
However, none of the doctors or nurses seemed to believe that I had dislocated the shoulder in bed, my fiancé had brought me to hospital, and one of the nurses made a point of asking him to wait outside so she could ask me if he had injured my shoulder. I reiterated that it happened on its own in bed; she did not seem to believe me but had to let it go. I couldn't get any useful advice from anyone at the hospital or on my follow up check-up today, they all seem to believe I am lying about the cause of my injury to protect someone. Hey, if someone did that to me, I wouldn't be keeping it secret!!
So I’m terrified there's a real underlying problem that caused this spontaneous dislocation, and if I don't find out what it is, it may be too late. I've heard it mentioned that diseases like Osteoporosis may cause injuries like this for no apparent reason, as the joints are weakened along with the bones. Help!

Is there something else I can do to find out if there is an underlying condition I should be addressing?