In early trades you can prioritize using E for trading autos, but if Renekton started Q then this will not work. Try to ping your jungler so that they won't make a stupid play, but don't overthink it. Sometimes you need jungle assistance to secure CS and nothing more, not necessarily go and fight the enemy laner. Let the Renekton push into you, and when he leaves, you do NOT leave him 4 minions outside of tower or it will be a freeze. Get your jungler to help you break a freeze so that the wave will eventually come back to you. Understanding minion wave management will help you understand how to safely lane. You can ignore this of course if he builds Tiamat but always important to know.
Randuin's was a terrible option and you should've went immediately for Titanic Hydra after Tri Force. It gives you an AA reset after the active which boosts DPS IMMENSELY. Then can go Deadman's or something similar from there, prioritizing who is an actual threat in terms of what you're building. Your ultimate gives you free armor/mr, allowing you to be building HP earlier via Titanic and Sterak's Gage (which is best when against burst). Your build hurt you the most basically. Your runes should be focused around 2 Armor Quint, 1 Attack Speed Quint, Attack Speed marks, HP/Lv seals and MR/Lv glyphs or CDR/Lv. These matter quite a bit too.
Gameplay-wise Idk what to tell you because I didn't see the game. I imagine you tried walking up for CS instead of waiting for the wave to push back to you naturally and blindly pushed to tower when he wasn't there, getting smashed once he actually came back because you overstayed. Just a guess because it's a common mistake, but naturally it could've happened differently.