Jumping lunges

Hi guys! I absolutely love strength and hiit training, but I struggle with some of moves. It might be worth saying, that I have an extra vertebrae in my spine, which makes it weaker - is this a factor?

I suppose , I really only struggle with jumping lunges, I’m 41 years old (so not too old) but if I do jumping lunges my back really hurts. I seem ok with jump squats, burpees etc but the jumping lunges are no use! Am I not doing them right, I can’t see how I’m not, or am I getting too old to manage them, or is my back just not able for them?