Hey J.
We went through this on and off for almost 6 months last year,it was a nightmare.I am not saying this to scare you,just to share my knowledge.Just because your daughter wasn't near her,doesn't mean their coats etc weren't close enough, or that some other child didn't get them and your daughter could be exposed through another child.The nits have a 7-10 day incubation period, so be sure to check her often.What about taking her to a nurse, we have a local health centre where nurses will check kids and adults to see if they find anything.
That being said,the over the counter treatments are not always effective,and are VERY harmful.I wouldn't recommend using them.Definitely get a good tea tree oil shampoo and go to a health food store and get a bottle of the tea tree oil itself.Dilute it in some water,maybe half a cup and run it through your daughters hair,then shampoo with tea tree oil shampoo with added tea tree oil in it.Lice hate this.I would recommend doing this a few times,perhaps once a week for the next month,to be on the safe side.Lice could go around many kids before they are stopped.We actually do the shampoo about once a month now to try and help prevent lice from coming back.I would recommend braids or a ponytail as much as possible.Hairspray and mousse are also good suggestions.I have heard apple cider vinegar works well,but smells awful.
Don't wait,check her hair maybe when she is watching a movie or a few tv shows,it can take a good hour to go through her hair,little sections at a time.Look for not just live lice but also nits as you might not see any live lice if her hair is thick.
Good luck!