What Causes Weight Gain, Heaviness In Legs And Difficulty Walking?

My name is Ann and I just turned 63. I have gained over thirty pounds in the last 5 weeks, without changing my diet. My legs feel so heavy and achy all the time that it is difficult to walk. I am tired all the time and want to nap every afternoon. I feel like I am out of breath all the time, and I am puffing almost all the time. I have been diagnosed with: Asthma, Diabetes, Fibromyalgia, Microvascular Heart Failure, Pulmonary Venous Hypertension, to name a few.