I've been dealing with a fever every evening accompanied by chills for over 20 days, but I didn't have any other symptoms. So, I went to see a physician, took antibiotics, and had all kinds of blood tests done, along with a chest X-ray and a CT scan. Everything came back normal except for my ESR, which was elevated. Now, the fever is gone, but the ESR count is still high, and none of the doctors can figure out why. Could you help me understand what's going on?