Hello again, and thanks for your reply with helpful information.
Even though you see no fleas, it's possible that she could have fleas, brought in on the pant legs or shoes of a human. Some cats are highly allergic to flea saliva, and one bite can cause a body-wide reaction.
Because you say she seems to be most affected around her neck, she could have ear mites which do fall out and adversely affect the skin/fur on the surrounding area, mainly the neck.
As you supposed, mites or lice are possible, and an evaluation by the vet, ASAP, would be a good idea, as she may also have allergies. Because you say she sleeps with you and you're itching as well, it's more likely that this is an external parasite problem.
I recommend starting her back on the Frontline, and see if that makes a difference. If she has fleas, it will kill all adult fleas within 12 hours. If she's still itching, a vet visit will be necessary.
For the moment, you can give her a bath with warm water and a few drops of Dawn dishwashing liquid (original) or any name brand you have in the house. Rinse well with clear water and towel dry. You can also give her 1/4 tablet of a 25 mg. Benadryl to ease her itching, but it's always best to first consult your vet before giving any over the counter medication.
I hope your furry girl (and you) are feeling more comfortable, very soon!