I think you'll need a visit to the doctor's - swollen legs could be a sign of type II diabetes, but also, you need to check your blood pressure and finally see if you have problems with thyroid gland, and which problem exactly. Are you currently taking any medications? Some of them, like steroids for example, can cause the leg swelling.
It's hard to say what is causing the swelling without CT scan or at least a ultrasound image, especially when it comes to knots you mention. Did you ever have any problems with varicose veins?
Wish you all the best,