What bit me last night?

Hmm you must have carried one of those ants in bed with you. Apply some Benadryl on the affected area to calm it down. Ice also helps so it won't itch, just apply it on the area for around 30 seconds and whenever you feel it start to itch again (a cold bottle of water can also work). Lol I don't think there's anything wrong with slapping the area, I usually scratch really lightly with the tips of my fingers (but not the nails) but it'll probably irritate the affected area even more which will lead to even more itching. You should also use Alcohol to sanitize the area by the way. :) I hope you feel better soon