You have calcium deposits building up in your body. This results in (IE) × 10 percent of your body being covered in horn-like extrusions. You can use these deposits as an unarmed attack causing 2 (1d4) + Strength modifier piercing damage. You are unable to wear most armor without it being custom made, costing 200 percent + (IE) × 10 percent and taking 100 percent + (IE) × 10 percent time to smith. You have a −(IE) penalty on disguise attempts and a −(IE) penalty on Charisma (Persuasion) checks. Calcification occurs internally, too, which is usually harmless but could lead to painful complications. Every 28 days, roll 1d20. On a 1, you must succeed on a DC 5 Constitution saving throw. Each time this happens (regardless of the result of the saving throw), the DC increases by 1, and each time you fail the saving throw, the original roll increases by 1, making it more likely to happen in the future. On a failed saving throw, you experience internal pain, 2 (1d4) psychic damage, until you succeed on a daily Constitution saving throw of the same value as the one you failed.
Real-world Examples
Kidney Stones, Hypercalcemia, Osteophytes (In real life, calcification is purely internal. Its expression here is a fantasy exaggeration, and those wishing for a more realistic representation can use just the internal mechanics.)
Assistive Options
Drinking twice the usual amount of water every day gives a +1 bonus to Constitution saving throws against internal calcification complications.
Magical Assistance
Magical healing applied directly to the source of internal pain will heal that occurrence but not heal other damage.