Pain appeared in the finger near the little toe on the right foot. The finger burns like a burn. The pain is periodic both day and night. Then the fingernail turned blue and the finger turned red.
You urgently need to see a surgeon, and then a rheumatologist for an accurate diagnosis of the disease. Judging by the symptoms, there is an inflammatory process and a disruption of the blood supply to the nail plate. Your letter does not indicate the reasons that could lead to such conditions (bruises, cuts, broken little finger), respectively - we will proceed from the fact that everything happened “out of the blue.”
There are several conditions that arise and occur similar to yours.
Damage to soft tissues by bacterial infection - a minor puncture or crack could become a gateway for pathogenic microorganisms. If you lead a sedentary lifestyle, have a history of diabetes or other predisposing factors, the infection may develop in this way.
The tissues in the affected area turn red, a burning sensation appears, and the blood supply to the distal (remote) areas is disrupted - which is why the nail could turn blue. The burning pain in this case is caused by the accumulation of toxins and the destruction of nerve endings in this area of the body. If this version is correct, you urgently need to see a surgeon to open the abscess. Next will be washing the source of infection, prescribing antibiotics, removing the nail plate and other useful measures. You can't joke with pus - wet gangrene and sepsis can begin.
Osteoarthritis of the joint - sometimes the peculiarities of gait, footwear and congenital structural features of the joints lead to a chronic inflammatory process, which is called osteoarthritis or arthrosis of the joint. Cartilage tissue is destroyed, then bone tissue, inflammation and joint deformation appear. This process is quite lengthy, and even in the acute phase the clinical manifestations are rarely so pronounced.
Rheumatoid arthritis affects small joints, including the legs. During the acute phase of the disease, tissue swelling, pain, redness and increased (local) temperature appear. The disease is autoimmune, i.e. chronic. More and more small joints are gradually involved in the process, ending with disability. Blue discoloration of the nail is not typical, but everything else may look similar.
Gout usually affects one of the big toes, but in some cases other joints are also affected. The clinical manifestations are similar, but the nature of the pain is somewhat different - more squeezing than burning. An attack of gout (especially the first one) always takes you by surprise. The disease is associated with a violation of the metabolism of purine bases and is characterized by the deposition of uric acid salts in the specified area. The disease is corrected with special medications that reduce the level of purines in the blood, as well as with diet.
A rheumatologist is a specialist in metabolic joint diseases. You need to go to him after consulting a surgeon.