There could be many reasons that your fireplace isn’t functioning correctly, and we want to help you solve the problem. Below is a list of potential issues and their respective solutions. Note that this list of problems/solutions is simplified, and a correct understanding of fireplaces requires an expert-level knowledge of airflow patterns.
The smell is most likely due to a natural byproduct of woodburning called creosote. Typically, the smell will be worse in the summer when the humidity is at an all-time high. There could be air pressure issues in your home that are causing air to be drawn down the chimney and into your living area. A sweeping will help but may not solve the problem entirely. A tight sealing, top-mounted damper will help because it reduces the airflow coming down the chimney.