Hi,
Here is a link:
http://www.ento.psu.edu/extension/fa...s/bed_bugs.htm
This link has a good explanation of the bed bug. The increasing size of your bites might be an allergic reaction. Normally, they just cause itching, redness, and a little discomfort.
Some types of creams help with the itching and redness, such as Hydrocortizone (or Cortizone 10), which is 10% hydrocortizone.
If they continue to spread or get worse, I would definitely see a doctor and get a professional opinion.