The most common cause is a blocked or restricted chimney. Even a new chimney and stove after only burning for a few weeks can have a blockage, usually at the chimney cap, caused by incorrect burning methods or most commonly by poor wood condition. Call a licensed professional chimney sweep to check ad clean your chimney and stove. He can check for other requirements such as combustion air into the stove, and be sure to check your wood moisture content and quality, using a moisture meter. Only good seasoned hardwoods should be burned with a moisture content below 20%. The chimney height is also critical to any wood stove, but assuming your stove has drafted properly in the past, this is not likely the sudden cause of the smoking.