Ouch! That sounds really painful!

How about soaking your foot in cool water and then trying the moleskin suggested by mimi and giving it a day to heal up. My experience with blisters, although I've never had one where yours is, is that they go away pretty quickly if you can leave them alone. Of course, I usually mess with them until they pop If it does pop, I'd do some major antibacterial cleansing and Neosporin ointment. You may be amazed at how much better it is by morning. I'll send your blister positive healing vibes.