I had the same problem the stump you are feeling in your feet is metetarsal pain and the numbness I think is starting from this. I started running in nimbus and now have changed to asics kayano with an insole ironman replacement insoles maximum athletic ??10.99 You can find these on natterjack running website they are fantastic I think that possibly you are over pronating and this is why your calfs are tight
I would start by trying the insoles in your nimbus change socks I spent a fortune on socks to find the right one I now use nike no padding and no friction I would also change the lacing until you find what is best for you
I would also go to see a physio I went to see a personal trainer and she noticed that my right hip and inner thigh was tight I have been working on this and now my problems have been resolved I nearly gave up running as I was in pain with the stump feeling and the numbness
Keep positive and good luck, I am no expert but this what worked for me.