Ornn into Renekton

So over the games that I've played with Ornn (since his much needed nerfs, mind you), there is one match-up that I cannot seem to understand.

And that is against Renekton. He can dash empowered W stun passed my bellows breath (w), forcing me to dash away. This combo usually does half my hp even as early as level 2 and his damage far outpaces anything I'm going to build defensive wise. I can harass with my Q to some extent but its damage is abysmal comparatively and doing that is going to cause me to run out of mana very quickly against a manaless champion.

So I should be playing back under my turret I hear people typing already. Correct, and that works up until level six, at which point a turret dive is almost guaranteed.

I would also like to point out that I am talking about a GOOD Renekton. Someone who is timing his abilities and using rage incredibly well, who is freezing the minion wave on me, who knows how to get his auto attack resets with the Tiamat, and who has ignite instead of teleport.

Assume that I get no help from my jungler, but I'm not getting ganked. What should I be doing? Building? What openings should I be looking for? Are there any unique interactions? OP.GG has Ornn losing lane a whopping 60% of the time so I know I'm not the only person having this issue.

And tips and tricks greatly appreciated!