Going to the doc sounds like a good idea and then you'll likely get sent to PT. The area of the ankle you're talking about is where some tendons run (not the achilles) so you could have tendonitis there. These get inflammed sometimes when a little ligament that holds them in place gets over stretched. But the time when you have pain (hills and down stairs) is often related to the calf or achilles. The moral of the story is that it doesn't fit into a nice clean diagnostic picture so it's best to get it checked out live and in person.