I usually pick it up for the owner who, in 100% of the times I've picked up a left behind club, comes back down the cart path asking golfers if they've come across
a lost club...same thing for head covers. Never had to leave...
Get a golf travel bag. You don't need a heavy duty expensive one, Just get one that will contain your entire rig without letting anything spill or slip out.
Craziest for me, if you can call it crazy, was a 3 club scramble. Players got to pick 3 clubs from their bag to play the 18 holes. I went with a driver, 7 iron and wedge and used the driver off the tee and as a putter.
Sounds like it's time for a tune up lesson with a pro. My long game went south on me a few years back and after a lot of frustration I took a couple of lessons and ironed out the problem. It's always good to have someone...