How far did you go? 5 hours is a very long time to be on your feet when you have been sedentary for months prior. It is not surprising that you are sore. I used to ride my bike about 100 miles per week. When I upped that to 160, I suddenly became incredibly sore, even though I am in good shape.

I think you just overdid it. Maybe some gentle quad and IT band stretches might help. You can google it and see which ones you want to try.

I would def take several days off walking like that.

About the only serious thing I might worry about is called rhabdo, and as long as your urine is its usual color, you are probably fine. You can also google rhabdomyolysis and see what you think. It does not sound like you have it.