Some states (maybe 20?) have special sexting laws. In the other states, sexting is handled under regular child p*** laws, which are very strict (most sexting cases result in plea deals). ALL states need sexting laws asap, because minors ARE being prosecuted for child p***. Most people would agree that sexting does not rise to the level of "real" child p***, but in most cases the law treats them the same.
If Makayla took the pics herself, and did not send them to anyone, she will be fine (although technically it is still illegal). If the pics were taken by someone else, that person has produced child p***, and if the pics were sent to someone else, that person has viewed child p***, and the sender has distributed child p***. All of these things can be very serious, legally.
As soon as Makayla said that she was under 18 when the pics were taken, websites rushed to take the pictures down. Not just to be nice, but because the laws governing child p*** are very, very strong.