Hi, I Have Been Having A Problem With Excess Saliva

Hi, I have been having a problem with excess saliva for the last few years but its getting worse to the point where I am avoiding talking to people in close situations. Its making me really paranoid. It could be a number of things as I have bad sinuses and take a daily spray for it, also I take a bladder tablet for an overactive bladder although that is known for giving a dry mouth rather than watery. It is sometimes accompanied by a strong metallic taste. My doctor has just shrugged it if many times but its really getting to me. Have you any idea what this could be.