There are two main reasons for the redness and pain on the leg. The first situation is that the leg has suffered a traumatic collision, the location of the collision will appear subcutaneous tissue and small blood vessels in the skin rupture blood seepage, will form a local accumulation of bruises, there will be a red situation. In addition, due to the excessive force of the collision, it is easy to cause inflammatory edema of the skin and subcutaneous tissues, which will also appear red, and when pressing with the hand, it will produce significant stimulation of the injury and inflammatory edema, which will lead to obvious pain in this area, the second situation is very likely to have local lesions on the skin of the leg, such as sebaceous cysts, also called acne and folliculitis, etc. In the second case, the skin may have localized lesions, such as sebaceous cysts, also known as acne and folliculitis, etc., so that the skin lesions are in a state of surrounding inflammation and irritation, which will manifest as redness and significant pain when pressed.