Answer: speaking from experience, acid can take a layer of your tongue away if you use enough, and im sure that vinegar has the same potential for damage to a canker sore as it does to your useful cells. the advantage is that the good cells grow back, whereas the canker sore doesnt. keep doing whatever it is you had in mind, cuz the damage i experienced wasnt painful and had no affect on my ability to taste food (the tequila i drank just an hour ago still almost made me gag).
Answer: it sounds like an infection, it can be from dirt, sweat etc. The best solution is to soak it in warm water or put a hot cloth over it. Try not to break it, clean it and put neosporin on it. If you put a band-aid over it and change it every day it will draw the pus out of the cyst.
Answer: The spongy feeling inside of the head can have several causes thatrange from minor to severe. A spongy feeling inside of the head canbe upper respiratory infections, or something as severe as a brainbleed.
Answer: Could be a few things. The most common reason for a limb falling asleep is that you positioned the limb funny and compressed a nerve in that limb against something, causing the limb to "fall asleep." If that was not the source sometimes injuries to nerves will cause the same effect.