Lice, oh my!
If not done already, get an otc lice treatment
from a drugstore & treat everyone in household (follow directions that came with it).
After rinsing it out, soak all of each person's hair thoroughly with plain white vinegar (dissolves cement holding nit to hair shaft). After 1/2 hour, comb every bit of hair from scalp to ends with metal lice comb. Repeat all steps in 1 wk. Wash all linens in hot water.