Lice as an adult?

Okay so I think I had lice. Did the treatment. I’ve combed though my hair TWICE now and I didn’t find any bugs. Just 3-4 nits(or so I think) the problem is my head is still itchy. I’ve combed though the best I could but idk. I’m still itchy and I’m so grossed out at the possibility. Please give some advice :(