What Should I Do If A Painless, Unmoving Knot On My Arm Hasn’t Gone Down A Week After Injury Despite Using Ice And Creams?

I hit my lower right arm Saturday night last week and a few days ago and that sunday morning i had a golf ball size knot on my arm and redness on the inside of my arm a few days later. I still have the knot on my arm but the color around it went away and it doesn t hurt at all but still there and doesn t move. I used which hazel, ice and muscle cream but I won t go down. What should i do?