Help!!!

My 4 yr old daughter recently went to the beach with my mom. I just found out today she caught head lice either at the hotel or on the beach. I also have a almost 9 month old son, I just found out today that caught them from my daughter! I cannot believe this is happening! I called the Dr but I'm waiting from him to call back. Does anyone know what I can do to help them? I know I can buy the over the counter stuff for my daughter but my son I'm not sure what to do about it. I have the comb so I've been getting out what I can on him but I need to treat I asap.