Persistent Erection

Help, I have a morning problem with a persistent erection, if I wake up in the night I am not in such a desperate situation in the morning as I empty my bladder in the night if I am desperate enough for it to wake me up, if not I am in trouble as I cannot get my erection to subside and some times cannot get into work at the normal time.  Every morning I have the usual desperate urge to pee and cant get there quick enough, and as I have a large bladder this is not funny if I cannot go, with an erection I just cant.  This happens nearly every morning now.  I have tried to aim it by leaning over the loo but I still cannot get the sluggish stream going, I end up just lying there in agony for hours.  I have to masturbate for hours to try and get it to subside, sometimes I manage to pee about 2 hours after waking up sometimes 3 by which time I am in agony and sweating.  I dont know if this has anything to do with it but I slipped on a fence about 2 month ago which hurt at the time but was ok after.

Please help, I dont think my bladder can cope any longer.

Thanks