I drove like 7 miles not realizing the driver side e brake was still engaged
The shoes on both sides were probably making contact with the drums - not just the driver's side.
You don't really state what the "issue" is, but we'll take a guess.
Let's assume you mean that the e-brakes will no longer hold the truck (i.e keep it from rolling away if you leave the transmission in neutral with the parking brake applied - and on a hill).
During the driving with e-brakes applied incident, you may have worn the rear brake shoes. Enough so that they can no longer make contact with the surface of the drums even when the parking brake pedal is cranked down.
You probably didn't burn too much away - they just need to be adjusted out.
You can try the automatic way;
While going pretty fast in reverse, vigorously apply the brakes. Do this several times and then check the e-brake to see if it makes contact. If it seems to be helping, do the auto adjust method a few more times till the shoe/drum gap is at the proper distance.
Or you can manually move the pads out by the star adjuster -it's faster. The star wheel is accessible through the rear slots in the backing plate.There may be a rubber plug, if so pop it out and the star should be visible.
Use a screwdriver to roll the star wheel up (as viewed from the back side of the plate). This increases the length of the adjusting screw which moves the shoes outward. Don't overdo it - it will have the same affect as driving with the e-brake engaged. Adjust the shoes outward until there is only the slightest resistance to rolling the wheel (with the tire). If you go to far, rotate the star in the downwards direction.
Some images that may be helpful:
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