Simple... another thing to throw into the equation is how long are your rides?

After this length of time, have you increased the length of your rides...?

I have no problem for nearly an hour... by the time I have been riding for over an hour I am feeling a little numb... after an hour and a half I feel occasionally sore and numb...

I do not get off during my rides and walk around, so if you do prolonged riding too, it is important to vary your position on bike, or stand on pedals and wriggle your hips on straight stretches...

Trust you find a solution...