I had surgery 3 weeks ago and for the past few days i feel so thirsty!! I try to drink as much water, but still wake up with very dry mouth is it normal does it happen to any of you??

It is normal but probably caused by mild dehydration. If you are maxing out your water consistently and don't feel as if that's the problem, try some type of SF lemon candy or anything with real lemon; it'll stimulate your salivary glands and help with a dry mouth.