I have had an annoying cough for 3 weeks. i don't have any other symptoms. it is present every time i speak, sit up straight, or even tilt my head.

Multiple: Your cough may be a result of something as simple as a blood pressure pill side effect to irritation of your diaphragm to allergies, etc. since it seems to be persisting you should check in with your primary care doc, get examined, and if appropriate, get appropriate studies done

Cough: A cough of 3 week duration that occurs every time you do the above mentioned things must be driving you nuts! Go see your doctor to get to the bottom of this.