Hi welcome to Health care magic forum. You had injury
1 month ago, still there is swelling, and you you are hitting on the same spot. The color is from purple to red but no regression of the color. suggests the injury is on a blood vessel and due to infection it didn't stop oozing and it is continuing to ooze slowly causing color. if it heals from inside the color become black and fades away.
I advise you to consult a surgeon for diagnosis and treatment. you may need to have an x ray
for excluding any crack in the bone, besides other routine tests for conformation of the condition.
Besides i advise you some diet recommendations as Avoid taking pulses, sprouts, potato and other tubers, fish to minimize the infection.
Take more of green leafy vegetables, milk, egg, meat, chicken, sea foods other than fish, fruits, juices, and dry fruits. which improve blood, general health , resistance, and stamina to over come such situations. Wishing for a quick recovery and thanks for calling.