Ventilation-perfusion (V/Q) scan is a specialized test that uses a radioactive substance to show the parts of the lungs that are getting oxygen (ventilation scan) and getting blood flow (perfusion scan) to see if there are portions of the lungs with differences between ventilation and perfusion.
Moleskin may be the first commercial blister treatment and prevention product I remember using. My dad always kept some moleskin in his pack and at the first complaint of any hot or sore feet, out it would come.
You may also find that putting an Ace bandage around the foot helps it feels better and keeps the swelling down. Don't wrap the foot and toe too tightly. Take Ibuprofen to help dull the pain and to help reduce the swelling. I tell my clients to tape the pinky toe to the toe next to it. I've never heard of putting a piece of cotton between the toes, and do not recommend that.