[maxerickson]

The pattern described by the OP can reasonably be described as under prescribing the antibiotics. Rather than following the recommended schedule which may last longer than the person feels sick, the mother was only giving enough to treat the immediate symptoms. The prescription is to give more!

[dragonwriter]

No, it can be described as under-administering the anti-biotics, not under-prescribing them.

[maxerickson]

Ya got me, I used some language imprecisely.