swollen right foot

Hi! I am a type 2 diabetic, on avandia 4, glucotrol 10, and a blood pressure med to stop proteins going into the kidney.
The last few days I have notice that my right foot is swollen on the top of the foot.
Not sure if this is because of weight gain of about 40 lbs in the last year or what.
When I stretch out the foot it feels like it is tight and the top is kind of painful.
What could this be and what do you do to get rid of it.