So why your losing all of a sudden is a much harder question to answer! What i can help with though is how to improve on things that you're currently doing.
seems to be your main jungle right now, and that's awesome! He's one of my fav jgs out there! From what i see though, you seem to be playing him more assassin than anything else. A general rule of thumb that i found for kayn is that if the other team has at least 2 tanks/off tanks, Darkin form is the way to go, with the build of Blue Smite Warrior, Black Cleaver, Then tank items(especially Visage) + boots and as a last item Death's Dance. This lets you tank a shit ton with healing out the ass!
But if the other team is 90% squishy then Shadow Assassin is better for that case, with the build of Blue Smite Warrior, Duskblade, Mobi boots, Ghostblade, Edge Of Night, GA/Lord Dom. This gives you burst, and a LOT of it! It allows you to melt squishy targets as you have leathality and can 100-0 anyone in less than a second with a W-Q-AA.
Side note: If you play darkin, play tank! DO NOT go assassin darkin!!!! PLEASE DON'T!!! I see it so much, and it just hurts too see!
Seems to be the champ you play most, the biggest problem that i can see right off the bat is builds. From the looks of things, you just build the same things in the same order every game. You have to mix stuff up or things will not work out. As an example of this, you were facing a zed, and had no Zhonya's, so zed could just kill you as you were lacking in armor. If your facing a big burst AD assassin like Zed/Talon then rushing a Zhonya's or at least a Seeker's Armguard. If your having a hard time vs an AP assassin like LB/Kat/Ahri, then Maybe getting a Banshee's or Abyssal would help more. Just try and change your build/build path per game.
Hope I helped a bit :)