You can develop a skin infection if you scratch the bites. Rarely, a more severe allergic reaction to the bites could produce larger welts, blisters, or anaphylaxis. Bedbugs may also trigger asthma attacks and getting too many repeated bites could lead to anemia. Anxiety, insomnia, and sleep disturbances are common due to the stress of discovering bedbugs.
Probably chiggers -- they are very small, red mites that usually cannot be seen with the naked eye. They are about as small as the period at the end of this sentence. To stop the itching, use OraJel (usually sold for teething babies), which contains benzocaine (an anesthetic). Also, rub in hydrocortisone cream. To prevent chigger bites, wear long pants and stuff the cuffs into your socks.
Bed bugs occur around the world. Before the 1950s about 30% of houses in the United States had bedbugs. Rates of infestations in developed countries, while decreasing from the 1930s to the 1980s, have increased dramatically since the 1980s. Before the 1980s they were common in the developing world but rare in the developed world. The increase in the developed world may have been caused by increased international travel, resistance to insecticides, and the use of new pest-control methods that do not affect bed bugs.
Never treat any bedding, mattress, etc. with anything other than the treatments listed: borax, enzyme cleaner, Comet, sodium borate. Other pesticides and exterminating fluids can be harmful to humans. Even so, bedding and mattresses treated with chemicals such as borax or Comet should be left outside to dry naturally in the sun, then wrapped in plastic before next use, so as not to irritate the skin.
While cleaning up infested areas will be helpful in controlling bedbugs, getting rid of them usually requires chemical treatments. Because treating your bed and bedroom with insecticides can be harmful, it is important to use products that can be used safely in bedrooms. Do not treat mattresses and bedding unless the label specifically says you can use them on bedding.