In my experience, it’s a conditioning problem. Start reasonably and manage expectations, if they pump up then walk like you have been, and check your electrolytes. You are probably low on potassium like most are.
Also supplementing runs with high incline walks on a treadmill at a good pace will help significantly to condition your legs again to run. I run a significant amount and can keep a solid 6:30-7 minute mile pace for 3-5 miles at 5’11 215 and pretty lean.
A good way to get started too is 3 runs a week, 1 long slow run, 1 interval “sprint” day, and 1 tempo run for just a mile. For the long slow run do just that, run for 30-60 min at a nice easy pace, and walk when needed to keep heart rate down/let the pumps dissipate. For the interval day, do 4-6 quarter mile runs at a decently fast pace and take an equal amount of rest, and then for the mile run go at a faster pace or “goal” pace for the mile and leave it at that. Then incline walks on the days in between and after a few weeks you should be solid.
And to echo what others said as well, running form, mid foot strike and don’t push it if it hurts. I’m partial to zero drop shoes and love altra’s. I get as many people possible on zero drop shoes, it’s an adjustment at first but my calves,feet and ankles feel amazing. This was a lot but I hope that helps.