Lately, my car (2000 Honda Civic LX 5 speed) has been making a strange noise. It makes this noise right after I shift gears, and when im at high rpm's about to shift up a gear. It sounds like some kind of rattling noise...comming from under the car below the engine or somewhere around there. I dont know anything about cars, but it has me worried a little bit. It seems to be running fine, I just want to know whats causing the problem and how to fix it. Any advice is appreciated!