Sounds like you need to see a spine specialist and get a complete evaluation of what is going on with your spine.
Your symptoms that you describe sound like something is amiss with your spine and the exercises are causing a problem.
There are many possibilities that could be going on and it's best that you see a spine specialist instead of speculating on what they could be.
You need to see either an orthopedic surgeon that specializes in spines or a neurosurgeon that specializes in spines.
You will probably need both general spinal e-rays and an MRI to start with and then see what the spine specialist diagnosis is and what treatment is suggested.
Good luck
Fran