FibroNana, good luck at your appointment on Monday, and be sure to post the results.
Just thought of something...my grandma and my mom had congestive heart failure, and they were told to weigh themselves when the fluid retention was under control, and then to weigh themselves daily after that. If they saw a weight gain of three pounds or more in a twenty-four hour period, they were to contact their physician, who would increase their "water pill"/diuretic dosage.
The reason I don't think your swelling sounds like what you get with CHF is because that normally starts at the ankles and works its way up from there...you wouldn't have one unswollen ankle, but yet the knee would be swollen.
Again, I'm not a doctor, but I want to put your mind at ease. Be sure to post the outcome of your appointment, and have a good weekend!