About 4-5 days ago I went swimming in the lake behind our house. I came out with a bunch of bug bites (I probably had 15-20) all over me. They didn't itch a lot, just enough to be irritating. After the 2nd day, they stopped itching but the little welts themselves are still there. Why is this? They don't hurt, only a few are still reddish and they look and feel like skin. I don't think I'm allergic to anything; we've been swimming back there for the past 3 years. I don't think they're hives, but I'm not an expert. What do you guys think?
It is hard to give you an exact diagnosis but one thing to consider is “swimmers itch.” Swimmer's itch is a patchy red skin rash associated with itching on the parts of the body that have been in the water. It is caused by certain parasites that normally live in freshwater snails and sometimes on waterfowl. On warm, sunny days, these parasites can be released into mainly fresh water or occasionally salt water. During your swim, the parasites might burrow into your skin, where they cause the swimmer's itch rash. But humans aren't suitable hosts for them, so the parasites soon die off while still in your skin. Although uncomfortable, swimmer's itch is usually short-lived and usually not severe. It usually occurs within 48 hours and may last up to 7 days. The rash of swimmer's itch, also called cercarial dermatitis, typically clears up on its own. The itching can be controlled with over-the-counter medications.
The other possibilities are as you mentioned bug bites. The most noted warm weather nuisance is the Mosquito. There are over 2,700 different species of mosquitoes throughout the globe. Mosquitoes breed in stagnant water and therefore, their habitats are usually found near lakes and ponds. Their bites are very itchy and can leave the skin irritated for a few days. They are also known to carry diseases that are transmittable to humans.
TeenHealthFX could go on for a long time describing the different scenarios and possible bug culprits but that would seem more like an exercise in futility. If the bugs bites do not go away on their own, become inflamed/ infected or cause any physical discomfort then you should go see a doctor. Your doctor should be able to tell you what type of bite it is and how it should be treated.
If you are going to continue swimming in this lake it would be a good idea to use insect repellent. Look for a product that contains DEET which protects against mosquitoes but also ticks and other insects.
If you don't have a doctor and live in northern New Jersey, you can call the Adolescent/Young Adult Center for Health at 973-971-6475 for an appointment with an adolescent medicine specialist or contact your local teen health center. You can also contact your insurance company for a list of in-network providers