[Zordon's Legacy Exposed]

The whole thing was secretly caused by Zordon. He put a temporary bad luck spell on her to test her endurance. As well as to test the rest of their Rangers to handle Rita's forces with Kimberly gone. He particularly focused on Tommy who had more than caught his eye as a useful tool by this point.

Of course he didn't count on him getting hurt. But lucked out when he recovered in time to rejoin the exercise. If Kimberly was lost Zordon felt she was expendable and easily replaceable. He was impressed enough to value her a bit more after he saw how she didn't break down. Which helped keep her around the next few years.