If you will accept some advice from someone with long experience with heel pain?
The stair routine probably put lots of strain on your calves and achilles, therefore the soreness a few days later. Stairs can feel fairly easy in some ways, but put a big load on your calves. Start slow with these, I would say no more than 10 minutes at a session, and once a week.
As for PT, the typical prescription is heel drops.
Once a day, start with about 20-30, work towards 50-60 over many weeks.
Have a great trip!