2 dr opinion. Ankle lean inward. Flat feet. Weight bearing pain in back ankle and under heel to arch. Tender but full rom. Sore inside ankle. At or ptt?

Try. Having your doctor immobilize it with tape, if improves orthotics will help.
Ptt. Is what it sounds like to me...Try orthotics.
Pain. What you are describing does sound like ptt. If taping helps then , as stated, orthotics should. See your podiatrist for the taping as well as x rays and exam .