This condition is called “acute temporary synovitis of the hip joint”, or “transient arthritis”. This disease is not directly caused by trauma such as a fall, but a fall is often the cause of the disease. If a child falls, he or she will not be fine at the time, but will only develop the disease after a period of time. This disease can disappear on its own, the treatment is mainly rest, you can take appropriate analgesics, vitamin C and antibiotics, generally about 1 to 3 weeks back to normal!