Cast too loose after two weeks

Patient: I had ankle reconstruction surgery just over 3 weeks ago and have been in a walking cast for 2 weeks now. Within a week of when the cast was put on, I noticed it was becoming looser and looser. There was almost no swelling in my ankle, foot, or leg when the cast was put on. I just started full weight bearing on the cast yesterday and the looseness of the cast is worrying me. I am able to move my ankle inside the cast, and it moves when I walk. The cast slides up and down when I step, which is making the top of my foot sore. I can fit two fingers easily in the leg part, and can reach into the part by my toes enough to feel the edge of the steri-strips over my incision. I have an appointment in 10 days to get the cast switched out (not sure if I’m getting another cast or a walking boot). Is this important enough that I should get the cast changed sooner, or should I just tough it out for another week?

Symptoms: Loose cast

Doctor: