<< I'm not sure why but when I cook stuff in the slow cooker I usually end
up sick for a couple of days.>>

Mark,

Check that you achieve a minimum temperature of 160 - 170 F with a
probe-style thermometer (available at Wal-Mart for about $5).  At this
temperature, you would have killed disease-causing microorganisms.

Disease-causing bacteria grow best at temperatures between 40 and 140F.  Its
therefore best to achieve a kill-off temperature of 160 - 170 F inside of 2
hours (a couple bacteria - staphylococcus aureus and bacillus cereus -
produce heat stable toxins when they proliferate between 40 and 140 F.  The
kill-off temperature has no effect on these toxins).

Most food-borne illness are associated with long, slow coolings.  Typically,
large pieces of meat or deep containers of stews, chili etc... are placed in
coolers maintaining a desirable temperature in the 40 F range.  It takes
many hours - sometimes over 24 hours - for the inside of these large
products to cool to about 40F.  For that entire time that the inside of the
product was maintained between 40 and 140 F, bacteria multiplied (sometimes
generating toxins).

The key to preventing illness from long, slow coolings is to break large
pieces on meat into small pieces and to place foods cooked in deep
containers into shallow containers (no more than 3" deep) before placing in
the refrigerator.

If symptoms include nausea and vomiting, suspect a toxin produced by
bacteria or a virus.  If symptoms include diarrhea and abdominal cramps,
suspect a bacterial or viral agent.

Rob