Good replies guys and some other things to look at.
Regarding my medical problem. Its predominantly the upward shock into my lower spine that's the issue. Throughout the ride I can feel the pain in the nerves of my legs fire up as the ride goes on and the impact gets greater in the lower spine. Then for days afterwards, the legs are really sore. I currently am waiting for a specialist to MRI me then take a judgement. Its the same for fast walking for the same reasons, impact on the lower spine as the heels hit the floor. If I walk slowly to soften the blow, it's fine, which is why I am thinking that a full suspension system might help the same as slow walking does.
On top of this, I cannot lean over due to neck stiffness and shoulder issues etc etc lol.