Hit on right heel by shopping cart foot bent under cart heard a pop in my plantar fascia now pain bottom of foot & achilles tendon what to do?

Start Now.: By the sound of it, likely a fascia injury and possibly some involvement with the Achilles tendon. These are initially treated in the RICE fashion.(rest, ice, compression and elevation) This will help with the swelling and pain. Avoid bearing weight on the foot until it can be examined and the true extent of the injury can be determined. Use Crutches until you can see a foot and ankle specialist.