At my home course, I stood on the first tee with a slight pain in my back. By the time I got to the second green, the pain was excrutiating and I couldn't breathe. A few holes later I had to crouch down every few steps to catch my breath. Turns out, I had somehow managed to collapse a lung the day before but didn't know it. The deflated lung was hitting a nerve that sent sharp daggers down my hamstrings and into my calves. I suppose this doesn't quite qualify because I had to walk off before I finished 18 (one of the few times I've ever done that), but it was definitely the toughest round I've ever played.
Sounds similar to one of my own personal "toughest rounds"...and NOT because of the course itself!
About two years ago popped out to my home course in Dubuque for a quick afternoon nine. Quickly teed off on our 10th hole (a par-3) and headed down to the green. Was carrying my bag (as always) and felt a slight twinge in my lower back...didn't think much of it other than maybe I had strained myself due to a lack of warmup.
On the next tee I spent a few minutes stretching then teed off again...this time MORE pain in my lower back and it was SPREADING!!! Walking down the fairway (kind of hunched over) not knowing what was going on but determined to keep on playing.
By the 13th hole I am in excrutiating pain and nearly doubled over after every swing...but like an idiot I'm gonna get in my nine holes, damn it!!! I end up shoot a 41 or 42 and head for the car.
By the time I get home I am in unbearable pain and curl up in bed in hopes of aleviating the pain. I begin to throw up and have the shakes. I literally had dialed 911 on my cellphone TWICE, but did not hit the send button...I had never experienced pain like this before. I ended up falling asleep for a few hours and when I awoke the pain had subsided. An ER visit and 48 hours later i had passed my first (and hoipefully ONLY) kidney stone. I wouldn't wish that pain on ANYONE under any curcumstances. Yikes...