We're just back from the pediatric urologist, and have fantastic news. Henry's kidneys and ureters are absolutely perfectly fine. He has no blockage, everything is draining as it should, and the issues we were seeing before have resolved themselves almost completely. Hooray!!!
No more antibiotics, no more tests, no surgery, and no more worries about our guy's kidneys. We'll do one more ultrasound in June to check on the slight remaining swelling in the left ureter, but the Dr. assures us Henry will outgrow the issue completely, and that we have no reason to worry about anything.
Speaking for both John and me: "Whew!"