Hi, thanks for writing to HCM.
A calcaneal osteotomy
takes around 10-12 weeks to heal and allow you to bear weight on the leg without any pain.
So, I suspect premature weight bearing as the cause of your pain in the foot.
It is always desirable to inflate the cast boot in a snug fit manner and not too tightly so as to impede the blood flow.
Hope this information is helpful. Good day