I broke my 5th metatarsal, got cast, no surgery was needed, after removing the cast within 3 weeks i notice that when i put my foot down it becomes dark red and purple, after i elevate it within 5sec it goes back to its natural color, is this normal?

Thrombus rule out: There may be a circulation problem and an ultrasound may be performed of your lower extremities to rule out a thrombus formation ( DVT). Sometimes after cast removal the skin may discolor. Especially if there is edema, DVT should be considered and ruled out. The other causes may include an infection, watch for fever, rash, swelling and drainage.