[Snake lover 3-25]

so Sooty the snake i've had for 1 week today has some kind of injury... when i first inspected him about a day or so after i found him i noticed a wound that at the time seemed to be a scar or a mostly healed wound at the most... but today he didn't eat... the first time since he got here... i tried everything but and he started to eat a mouse but then droped it and wouldn't eat anything else... so i picked him up hoping to warm him and get him to eat... i noticed that his wound has turned from black/ almost skin color to an orangy brown... with all of the recent snake sicknesses and infections i am very woried!!!!! i will try to post pics but all of the bateries are dead... i steralized his cage and put in paper towel...please help!!!