Magnesium deficiency can cause muscle twitching and spasms, as well as poor mood. I know from personal experience that this affects me, and I've been found to have a serious deficiency from blood tests. Correcting with supplements (or even injections) didn't work - the only thing that has, is (you guessed it) abstinence from PMO. In terms of the joint aches and pains, this may be due to an impaired immune system - have you ever noticed that when you get flu, your joints will ache? When I've had a serious PMO binge I get the symptoms of mild flu - achey joints, running nose, and sensitivity to noise, light, smell etc for days after. This is just my amateur theory, but I think that the immune system takes a hit with PMO. PMO drains the life and vitality from you, which can potentially affect all aspects of your health and wellbeing. That might sound like vague hippy-dippy nonsense to a lot of people, but if you've experienced it for yourself, and you know what to look for, it seems pretty obvious - shame it took me 25 years for the penny to drop... I'm sure science will be there to validate this idea in time, but as I've said elsewhere, it could be a long time in the making.