It seems strange that a bug small enough to be called a noseeum (sandflea) can have a bite that can cause problems. Noseeums have sharp biting parts, and their bites are painful immediately, unlike a mosquito, where you might not notice you've been bitten. Noseeums tend to bite en masse, or the same one will bite several times. It's typical to be bitten a dozen times or more on a rather small area of exposed skin, and the bites are usually extremely itchy.
Treat the Itch
The big danger with noseeums is that you can have many bites on a relatively small area of your body, such as your arms or lower legs, if they were uncovered when the noseeums were out. Or if you were wearing a bathing suit, you might have a large quantity of bites all over your body. The bites can itch much worse than mosquito bites, and if you have several in the same area, the itching can be intense. Scratching will make it worse, so try hard not to scratch. Use the strongest topical analgesic you can find, and consider taking an oral analgesic as well. Look for a gel, cream or spray that contains a topical analgesic and an ingredient that will treat the cause of the itch, such as cortisone or an antihistamine. An oral antihistamine may be in order if the itching is especially intolerable.
Guard Against Infection
Bites can become infected. Clean any open blisters with hydrogen peroxide and put antibiotic ointment on them. If they still itch, look for antibiotic ointment that also treats pain, since the topical analgesic that is meant for pain will also help the itching.
Beware of Possible Complications
There are many species of small biting insects around the world. Most will just cause annoying bites that itch, but some can transmit more dangerous diseases. If you develop a fever or open sores, consult a doctor and make sure you tell her about the noseeum bites.
Once you've suffered an episode of multiple noseeum bites, you'll be motivated to keep it from happening again. Noseeums come out at dusk and tend to be more active again at dawn, and they like areas near water. They can often come through window screens, but you'll be much more at risk outside. Lights attract them, so keep them off, and wear clothing that covers your skin. Use a bug repellent that contains DEET. In your own yard, you can prevent them from breeding by dumping out any containers that collect water and treating any standing water or puddles with an insecticide.