How do I get the buttock deformity from hard fall on metal edge of steps fixed? (Photo)

Hit buttock on sharp edge of thick metal steps. Instantly developed large lump 5"h x7"w x1.5" thk, looks like someone took a knife and sliced under the lump. Buttock is now a lump on top, has a horizontal slice through the middle, flat underneath. No change after 3+ months (foam rolling, NSAIDS, ice, heat, ultrasound). What are my options? How do I get rid of this deformity that can be seen through my clothes? X-rays showed no fractures, ultrasound showed minimal fluid, not enough for this.