Re: My sims are always sick

@Larcias  This sounds like the pestilence plague.  It's caused by a witch casting a spell, and it's contagious.  I'd guess that if you have a lot of witches in town, or maybe just a couple that are particularly evil, then they're constantly cursing other sims, who then pass along the illness to others.  The plague can be cured by another witch casting the sunlight charm, or (I think) by eating a ghost chili or some honey.  Hospital medicine doesn't work.

The other way to get rid of the illness is to open the cheats console (crtl-shift-C to bring it up) and enter "testingcheatsenabled true" without the quotes.  Then you can right-click on the moodled to make it disappear.  (Enter "testingcheatsenabled false" to disable the cheat again.)  If there's a rogue witch running around cursing everyone, you could turn him or her human with a potent cure elixir.  You can also edit any sim in Create a Sim, and remove an occult trait, by enabling testingcheats and shift-clicking on the sim.