Hi,
Cracking joints is normal in certain people. It seems to be the case with you as well. However sometimes it indicates an underlying disease like a torn cartilage. If the problem persists I would suggest you get yourself evaluated by an orthopedician.
back of my neck pops very loud when i lift my neck and trun it. its a very loud pop and it does scare me. can anyone tell me what it may be?
Push-ups are very hard on your elbow's and wrists. The cracking sound is the stretching of the ligaments, separation in the bones, and change in the fluid that lubricates the joint. This may lead to arthritis in the join although some studies suggest that it doesn't. Never the less it is hard on the joints. You can get cash-up blocks that take the weight off your wrists.