My mother who is 72, was exposed to a natural gas leak for a couple of weeks. The thought at first it was a sewage problem. But my brother came over and told her it was gas. The gas company was called and the first guy did not detect a leak. They were called again and found the leak right away. She had been breathing in the fumes for weeks. can this cause any permanent problems? She is having symptoms of a cold and her memory seems to be a bit worse.