What Could A Red Line On The Inside Of My Arm, That Runs From My Armpit To My Wrist, Mean After A Fall?

Hello, a week ago, I was repairing a roof and fell through and landed on the rafters of the ceiling. I was sore for a few days, but the soreness subsided. Today I noticed a red line on the inside, underneath my arm, that runs from my armpit to my wrist. What could the red line mean ?