Character health won't drop (Dragon Age Inquisition)

Unfortunately, it's likely the damage is permanent. You're lucky that's all you've done, some trainers etc. can completely break your character, or leave them unable to attack, etc. 
Other than loading a save from before you used the trainer or starting a new game, I don't think there's anything you can do. 

You could try repairing the game in Origin (right click the game in Origin, select 'repair game', if you're using mods, I recommend you remove the mod folder first, you can put it back afterwards). I wouldn't be all that hopeful of it fixing the issue, as it's probably baked in to your save, rather than the game itself, but it doesn't hurt to try. 

Sorry I couldn't be more help.

emm how disappointing, but still, thanks for your times