In reply to uberdan:
mm, strange. Still won't be the tendon if it doesn't hurt without the boots. Not long-term damage, anyway. Still might be a good excuse for new shoes? It could've been inflamming the tendon insertion point but if its going away easily just take anti-inflammatories (ibuprofen) the whole time, and use ice each night to soothe. or cover the area.
Does it feel "deep" or superficial?