Gout

Gout is an inflammatory disease caused by the accumulation of uric acid in the joints which form crystals.  The formation of the crystals causes acute pain, swelling and stiffness in the joints which eventually subsides when the uric acid is dissolved back into the blood streams.  However, if uric acid levels remain high, the disease can become chronic and presents in a manner similar to arthritis.  Although any joint in the body can be affected, it often presents for the first time in the first joint of the big toe as the condition is exacerbated by keeping pressure on the site such as that which is typical of wearing shoes. 
As kidney stones are largely made of uric acid, stones and Gout often occur together. 
Gout can be caused by eating too many foods with a high purine content, such as organ meat, sardines, anchovies, and scallops.  It can also be caused when the body is unable to expel uric acid efficiently through the kidneys.  This is a typical cause of gout in alcoholics. 
Gout is not easy to diagnose and there are other conditions with similar symptoms.  The definitive test of detecting the crystal structure is difficult, even for a trained observer.  High uric acid levels in the blood are useful in a diagnosis, but are not definitive. 
Several drugs are used to treat the condition, but the pain can be relieved through the use of ibuprofen.  Aspirin should be avoided as it can actually make the disease worse.  In addition, patients should avoid foods high in purines and drink lots of water to encourage the passage of uric acid through urination.
It is mentioned in Occam's Razor when the patient was given gout medicine, Colchicine, instead of cough medicine that has the letter "L" on the pills in a pharmacy mistake.
Gout at NIH
Gout at Wikipedia
Gout at Mayo Clinic
Gout