If this is 25NL I reckon he had AKc to QJc, with A4-A8 an outside chance.

You have a flush draw and a substantial straight draw on the table - unless you're sure you're facing an overpair you're in real danger. I'd be tempted to push on the turn since he's next to pot committed anyway - your call here just gives him the chance to catch a draw, and if he does, then what?