|Hi there--I am sorry you are having a difficult time finding a diagnosis. However after viewing your pics, I am almost positive you have insect bites, maybe mosquitos but most likely from chiggers.
You stated that chiggers don't "spread" and that is right--once they find a feeding spot they attach themselves. BUT--chiggers are very active and can search your whole body looking for an ideal spot to feed. The chiggers that annoy people have long legs and can move rapidly. They are capable of getting all over a person's body in just a few minutes. The long trek from a victim's shoe to the stomach (a favorite point of attack) is a climb that take about 15 minutes but is more than 5000 times the chiggers's tiny length. That's about the same as a human scaling a large mountain-and on an empty stomach.
Chiggers are small enough to penetrate the meshes of your clothing, but they usually stay on the surface of your clothes until they come to an easy opening such as your cuffs, collar or waistband. Once they are on your body, chiggers wander about for an hour or more looking for a tender spot to dine. If these traveling chiggers reach an obstacle such as a belt or an elastic band, rather than cross over the obstacle or go under it, they stop and begin to feed.
Itching usually peaks a day or two after the bite occurs. This happens because the stylostome (feeding tube) remains imbedded in your skin tissue long after the chigger is gone. Your skin continues to itch, from an allergic reaction to the stylostome, for many days. The stylostome is eventually absorbed by your body, a slow process that takes a week to 10 days, or longer.
Because of the looks of the rash, location of your bumps, and the circumstances (being outdoors camping) I cannot see why the doctors confirm it was chiggers. It is not swimmer's itch because your bumps are too large and far apart, and it is not poison ivy.
I don't think the Prednisone is a wise choice but that's the first thing doctors administer for rashes regardless, and that is wrong. I feel Prednisone is over-used and can cause more harm than good in all but severe cases. The extent of your bumps, although very itchy and aggravating, is considered a mild to moderate case. Prednisone will help reduce your inflammation but it has a whole slew of undesirable side effects, and you most likely will get a rash after you stop taking it like the majority of people. The only ultimate cure is time, since there is nothing you can do to dislodge the chigger's feeding tube, the true cause of your itch. You must simply wait until your body breaks down and absorbs the foreign object.
Please let me know how you are doing with your treatment. I have been doing medical research for over 20 yrs. but I learn new things also as I try to help others. I have a feeling I am right on this one. Take care and I hope you find relief :)