.....after I posted that, I see that you've been a member here for awhile!
Duh. So, you probably know your way around! Plus I think I've 'spoke' with you a few weeks ago actually! lol

The reason I'm asking about 'burning' pain, is because your post caught my eye when talking about that heaviness feeling. I know exactly what you are talking about.
I'm sorry you aren't getting any answers from the Drs. I know how frustrating that can be! Alot of us are in the same boat.

Part of my issue was because of becoming so inactive due to my pain issues (started in knees) and weight gain (from Lyrica, but have since quit that med and lost the weight), so the muscles in my legs became very weak (atrophy) which magnified my pain issues and it just seems to go in a huge circle of madness!
Does is hurt to climb UP stairs?
Do you hear a 'popping' noise in your knee (crunching sound?)

Rae: I wouldn't say it hurts to go up stairs, but it is a struggle to get to the top. I am out of breath and my legs are very weak by the time I reach the top. I haven't noticed a popping noise - yet.

Weak muscles fer sure

When you get back down to your ideal weight, it'll help alot.
I did this as an 'self-awareness' experiment to make me realize how much strain it actually does put on our bodies to carry around the extra weight....

Walk around the house with a 10 pound bag of potatoes for about 10 minutes. After awhile that 10 pounds seem like 40!!

Regarding the 'lead leg' feeling, I was told to do hamstring excercises.....
yeah fun. But it did absolutely nothing to help my burning neuropathy pain.