Do you sew in your feet? Do you wear shoes when sewing? You may need to have a different pair of shoes on when sewing.
Try to notice how you're holding your foot when sewing. Try getting a piece of rubber for shelving and put it under the foot pedal. This may help to hold the pedal and help hold your foot in place. Also if you're heel is hurting, maybe think about getting an office mouse pad that has the cushion for your wrist to help your foot. Another option may be using one of the corn or rice filled heating/cooling packs. You can make one. Make a large square pillow and fill it with rice, corn or beans to cushion the heel of your foot. Moving the pedal. This may also indicate that your chair is not set at the correct height. Do you have a tilt base for your machine? That may help. It would help you sit in the chair differently and may help your foot.
Just a few thoughts about your posting. Good luck with your foot issue and keep us posted as to what you find that helps.
Pam M