Hi there
As a vet, I will confirm that oxytetracycline is an antibiotic, and is pretty good against bugs that live around feet.
If it looks like a stone or something has caused damage to one part of the foot, then cutting away any loose hoof around the area and spraying with the oxytetrin spray every couple of days should help.
Sometimes if the infection or damage has travelled in further, they may need an injection of oxytetracycline, or a similar antibiotic to attack the problem from both sides.
I wouldn't recommend washing, you are more likely to wash bugs further in to the damaged area, or give them moisture that they need to survive, likewise I wouldn't suggest strapping, as a lot of bugs that live in the soil don't like too much air getting to them, and strapping will keep the area warm and moist which would be ideal for the bugs.
Leave the foot open to the air to dry it out, and spray with the blue spray for now and see how she goes.
If she's still looking lame on Monday, could then be worth getting an injection for her.
Hope that helps
Suzanne