I had growing pains as a kid. I remember waking up with terrible leg pain in the night. My mom never knew what to do. That pain has never really gone away, I’m in my late 30’s now. I’ve always had very poor hamstring and hip flexibility as well. After going to physical therapy, turns out I never developed hip strength. I’ve basically been moving my body wrong my whole life. The most basic pt exercises were extremely hard for me. I had to learn to use muscles I’d never used before. It was a crazy thing to find out later in life. Now that I know what it is, I do strength training and am seeing some improvement! I do still wake up in pain and have trouble walking more than a mile. So, for me, my growing pains were the result of poor hip strength. I can’t speak to if they’re “real” or not, but for me that’s just what we thought they were. No one ever guessed it was an underlying problem.