That's interesting how flossing and brushing make it worse. It may be due to the irritation of the brushing and flossing that's causing some movement of the tooth. If there is an infection, it may
travelTravel sickness down to the jawbone and when the tooth moves, it moves in the jawbone and causes irritation. Do you have problems with eating?
I would recommend removing the tooth if its a problem. It is a wisdom tooth (no. 32) so it doesn't have much of a function, especially if there's no wisdom tooth opposite it. Consult your dentist to see if thats the best solution.
You should probably discuss it with your dentist. Is there a crown on the tooth? You may want to perform a cleaning in the area to see if that'll help.