I am 72 years old & was diagnosed with type 2 diabetes in 2013. Have been taking 2000mgs Metformin twice daily ever since. Lately, and approximately 1 hour after having my nightly tablet, I have excessive saliva. Last night, I felt slightly nauseous in bed & stood up in time & a constant stream of saliva came out of my mouth - it was pretty scary because I had no control over it. The only thing that stopped it was for me to swallow hard 2 or 3 times. Please advise.