From your description, it sounds like your dryer vent may be clogged with lint. Pull the dryer away from the wall until you can disconnect the vent pipe, about a 4" diameter tube made of plastic or shiny plastic or metal. Chances are that there is a lint buildup where the pipe makes the 90 degree bend to start going up or it could be snagging on some kind of projection inside the pipe. This can be a real fire hazard so it is important that you clean all the lint from the pipe, vaccuum if possible. This pipe lets the hot, damp air from the dryer escape to outside. If yopu can't clean it, replace it. It is also a good idea to never leave the house with the dryer running.