I've been thinking about this thread and wondered: how could one gain 16 pounds in so few weeks?

And one thing I could think of, in combination with other causes, would be: pregnancy.

ER doctors and others are trained to remember that every woman between 10 and 65 is pregnant until proven otherwise. (The reason for this being, among others, that the consequences of an undiagnosed ectopic pregnancy are dire.) Have you had a pregnancy test done yet? Is there any chance, even the MOST REMOTE, that you could be pregnant? It might seem silly to you, but I would definitely suggest ruling it out. Even if you are using contraceptive right now.

I hope you find a resolution to this... Good luck!