Your symptoms sound pretty normal for a newbe. Your are using your hands in a stressful way they are not accustom to. This can cause some transitory pain along the way to competence. As long as it goes away quickly when you stop, you are probably not at risk of causing long term problems. What you are describing sound pretty normal.

However, keep an eye on your pain level. If it does not stop when you stop playing the guitar, you should give the guitar a break until you have no pain. Some pain is normal when you are learning a new task, but persistant pain is a warning sign worth heeding.

Also, try shorter practice times until you build up strength in your hands and arms. Also look at how you are holding the guitar. For example...down around your knees, is great for looking like Kieth Richards, but it places greater strain on your hands and wrists. Reviewing GT lesons on how to hold the guitar may also be of benifit.

Use a strap, even when you are sitting down. This will stabilize the instrument in a reliable position, which will take a load off your hands and arms. Holding the guitar by wrapping your body in a knot around it... is not productive. Using a strap can be very helpful in avoiding this pitfall.

If your pain persists, it could be useful to get a professional evaluation of the problem. A Physical Therapist could be of great help in cases of PERSISTANT pain.