Oral thrush is usually a white color and would not produce a green phlegm. Sounds like you might be in the early stages of a respiratory infection...possibly a cold. Coughing up green phlegm could be from some sinus drainage that has drained down into your chest. I would not worry too much about it unless you start to develop new symptoms such as fever or shortness of breath. At that point, you can see your Dr for a chest xray and treatment if infection is found. The Thrush should be better (or resolved) within a few more days. It usually responds very well to Nystatin therapy.
Hope this helps!