Several Questions

My first question is... Whenever I go to the gym, I normally run 1-2 miles and then use several nautilus machines. (chest, 3xabs,biceps, triceps, shoulders). When I'm done and driving home, or even when I get home. I have the shakes, my hands shake, I don't feel dizzy or sick, but I just feel a little uncomfortable (not painful) just an odd buzzing type feeling. What is it? Why? Is it bad? What should I do? Okay, next question =). I consider myself to be in okay shape. Since I graduated last June (99) I've lost over 40 lbs, since then I've been going to the gym (not very consistent though) I have bulked up slightly but I can find I can only do like 10 max push ups and it is just so unbareable I have to stop! What am I doing wrong? Can someone tell me some good things to do to make push ups easier? I need to be able to do 30+ soon!!! Yikes! any help would be greatly appreciated! thank you!