Parasites under scalp/in head

For the last week I have had a tickling sensation on the left side of my head. It seems to move to different areas but mostly remains on the left side. I went to Urgent care because I thought perhaps its lice or some kind of other outside parasite. At first the FNP could not see anything on my head so she called another doctor and got some magnifying glasses. They couldn't spot anything but light dandruff then suddenly they spotted what they said was lice. I've done two lice treatments but still, that sensation is there. I've checked my own head and haven't found anything. I'm worried that I might have something under my scalp. Any suggestions on what I can do to find out what it is? It is worrying more by day and thought of seeing my doctor and asking for a CAT scan and parasite testing. Any recommendations? Tweet