There are a few different stretches and exercises you can perform in order to relieve the pain you feel in your foot and heel.
The first stretch you can do is called the Achilles Stretch. This stretch is performed by standing and facing a wall. Place both of your hand against the wall and move the affected foot back keeping it flat against the floor. Bend your front leg at the knee while keeping your back foot against the floor so you can begin to feel the stretch. Stretch as far as you can until you feel the stretch at the top of your calf muscle. Hold that stretch for 30 seconds and repeat 5-10 times.
The second stretch you can do involves using a step of some sort, whether it be your stairs or an exercise step. Place the balls of your feet on the edge of the stair while holding on to something or someone for balance. Slowly start to lower the heal of the affected foot down until you feel a stretch. Perform this 5-7 times for 30 seconds.
The third stretch I would recommend to help ease the pain would be one you can easily do while performing other tasks, which let's admit, is very important in these fast paced times! While sitting in your favorite chair, lay a sturdy plastic bottle or can on the floor in front of you. Without wearing any shoes, put your foot in the middle of the bottle and begin to roll your foot. You will want to roll from the tip of your toes all the way back to your heel, giving your foot a full range of motion stretch. You can perform this stretch for as long as you would like but you want to go at least 10 times in each direction.