Also, not to freak you out - just so you're aware...if you're not already, watch for excessive sweating in your foot, discoloration (red/splotchy outside of the 'normal' post-op experience), excessive swelling (outside the 'normal' post-op experience), hypersensitive areas on the skin, & hair/nail changes as they can all be indicative of CRPS.
That said, it quite likely is a temporarily upset nerve...I don't know if you're out of the cast yet, but massaging the scars to help prevent them from causing issues with deep scar tissue can also be helpful.
I had the same symptoms after flat foot reconstruction surgery. My surgeon started me on Lyrica for nerve issues. At the time he had said that it was more then likely temporary and fortunately for me it was. After several months I weaned myself off the Lyrica and I had no more issues. Make sure you talk to your doctor about these symptoms.
I am 5 weeks post op as well. I had severe comminuted fracture of the calcaneus and cuboid. We sound rather similar even down to the plate and number of screws. I have artificial bone in the heel. I was troubled with the burning as well. My doc looked at my foot and said it was healing really well. The burning was nerve pain...like firing and trying to work..It has now subsided some. I hope you get relief soon.