I'm really confused. He has no health and is just hovering in the sky with that other dragon circling him.

What did I do wrong? Should I just load a previous game and try again? has anyone else experienced this?

Use Dragonrend, the shout

It doesn't bring him down. He's just chillin in the fetal position.. No storms or anything going on and he has no health left. I guess I'll just reload, but I thought I'd make a thread first and see if I'm just crazy/dumb or if this was some kind of glitch.

I'm getting this - horrible bug.
Any save loaded after reading the scroll and Alduin is just frozen in mid air, and even depleting his health and using dragonrend doesn't do anything.