I feel like a bug is crawling on my scalp in the same exact place on and off for 16 hours now. husband keeps checking the spot and can't see anything!

Sensation: that sensation you are having sounds like neuropathy. A nerve is irritated in your scalp. Look for a rash in the area, it may be shingles. Many neuropathies resolve ( like when you hit your "funny bone"), if it persists for over a day, see your doctor. If you are having any weakness in your arm or face or slurring words or balance issues, see a doctor now.