My horse is really lame...?

It's hard to really get the perspective from your photo(even though it's really good, clear and close up), but I'd say he could have an abscess cooking from the toe problem or he could just have a high nail that is pinching him and causing him intermittent pain and the stumbling you described. He might also be a thin-soled horse who just became tender after his last shoeing - especially on the toe, because it's exposed the way it is and also looks like it may be a bit on the short side so that he's standing a bit upright. That could explain why he gets temporarily sounder after being locked up and then lame again after the concussion from moving around outside, and could also explain the stumbling. The shoer may have to clean it out again and repair that area with epoxy to keep dirt and debris from getting in it and also to relieve the pressure on it. It's good that you have the vet coming as he/she can put testers on him and identify exactly where the pain is coming from. Good luck and let us know what it turns out to be ok?