The lateral
sides of the infant’s heel is the preferred site for capillary puncture for it
is the safest region for blood collection. If the center portion of the heel,
toes and the arch of the foot is used for dermal puncture, it may cause injury
to the nerves, tendons and cartilage.
Because these is where the best capillary bed is located protecting the calcaneus from being damaged. For Infants under 6 months puncture at the lateral side of the heel is the best site since they’re fingers are so small. A heel stick is best recommended to use for this test.
You shouldn't over continue to play even though it still hurts which gets B out of the way. You don't need to stop playing tennis completely because when you can get better you can play so it's not D. And only playing once a week could still cause injuries.