He was pretty mediocre at Dortmund and I can't remember him playing since his loan was cut short.

Should he go on loan again? Or sell? Or stay at United

I think he should go on loan maybe to a low-mid table team somewhere he can shine

It'd get his confidence up and hopefully by the 2017-18 he'd be a star

He shouldn't be sold he's shown previously that he's good enough but if he's not in LvG's plans it'd be stupid to keep him at United.