Deep pain in middle of left heel. husband is 76 & diabetic. podiatrist no help. pain ongoing for 6 months.

Heel : Then see another podiatrist . I get the idea that you are condemning all podiatrists because you did not get relief . Seek another opinion. This could be vascular , stress fracture, etc. Go get the help you need

Possible combination: You'll be fine with either. An orthopedic foot ; ankle or another podiatrist. Unfortunately, there are incompetent docs everywhere. Deep aching localized heel pain with first step out of bed/rising from a prolonged sitting position commonly signals plantar fasciitis. There can be other contributing causes such as posterior tibial tendon dysfunction that causes the arch to collapse.