May 12th is Fibromialga & Chronic Pain Awareness day. It and closely associated problems (ME/CFS & FM) are really horrible but you can't 'see' them. But they are real.
May 12th has been designated as International Awareness Day for Chronic Immunological and Neurological Diseases (CIND) since 1992. The CIND illnesses include:
Myalgic Encephalomyelitis (ME), Chronic Fatigue Syndrome (CFS), Fibromyalgia (FM), Gulf War Syndrome (GWS) and Multiple Chemical Sensitivity (MCS).
May 12th was chosen as it is the birthday of Florence Nightingale. She was believed to have suffered from ME/CFS