In reply to Jasonh: You need to be more specific about the exact location of the pain and the type of pain: a dull ache or a sharp pain? Also, is the pain in one small spot or is it over a general area? Does it hurt if you squeeze the area gently with your thumb? Is the ache there all the time? Does it get worse whilst climbing, after climbing?
Have you seen a GP or a physio?
If the pain is in the forearm away from the elbow or the wrist, it is likely to be a muscle strain which can take six weeks or more to heal up. If so, I would avoid any high intensity exercise and do only low intensity work combined with lots of stretching of the muscles in the area of pain. Monitor the pain regularly and if it gets worse it means you are doing too much. Ice the affected area after exercise. If there is inflamation take some anti-inflammatories.