Oddly enough, the first step is to see an arthritis doctor and ask for a crystal analysis. There are many crystals in joints, they can be analyzed incredibly cheaply (picking one out; looking). If it is calcium, phosphorus, uric acid, there are specific treatments and specific dangers. Salt crystals look, like, well, salt under the microscope and that is diagnosable also. These all are well known to form skin deposits. Uric acid is easily treatable with pills costing pennies. They all take months. Surgery can be done. It is quite risky for making the area much much worse because the crystals are irritants and disrupt blood flow and healing. If it were really crystals in the skin near the surface, a good swim (not in the ocean) would in theory dissolve it. I suspect either it is another substance (see crystals above, or scar tissue perhaps, or infection) and/or the material is in the fatty deeper layers of the skin that tattoo ink is placed into. Tattoo ink is ionic, and dissovable just like a salt (it is a metal salt). Doesn t get out chemically ever. It is only removed by chemical reactions that would not do a thing to salt (photo bleaching). This is a thing. It usually is involved with other common medical conditions (gout, thyroid, any organ failure especially kidney--I suspect you temporarily lost your kidneys and this makes each and every crystal mentioned go sky high). Could be worse, any of the conditions to cause it (loss of kidney, electrolyte imbalance that is incredibly high, organ failure, blood breakdown, etc) is usually fatal.