There is a wide range of possible causes for these symptoms. Sometimes loss of circulation or pressure on the ulnar nerve as it travels down the arm from the elbow can cause the numbness, tingling, and weakness you've described. There may be a problem higher up in the neck. For example, pressure on a spinal nerve from a bulging disc can cause these symptoms. Likewise, pressure on the nerves where they travel under the collarbone or by the shoulder can result in numbness and tingling in the hands.
There may be some changes in anatomy causing this type of pressure on the nerves. Activities that repeat the same motions can lead to these symptoms. Even diabetes can affect the nerves and cause symptoms. It is best to have a doctor examine you, especially since it has been six months since the symptoms started. Early treatment may prevent long-term problems.