I just came across this post, and I can answer your questions about Shelby's red cell production. My daughter also has the same blood disorder, and has followed much of the same path as Shelby (though she is only 11 still at this time). In fact, she got her gall bladder removed at age 5, and her spleen at age 8. Every article I have ever read about Shelby and her struggles have made me cry, as we have lived that exact same life!
My daughter's spleen basically recognizes her red blood cells as the enemy, and kills them. A normal person's blood cells are NOT spherical in shape, so they pass through the spleen. With spherocytosis, since the red blood cells are spheres, they don't pass through, and the spleen kills them. Once the spleen is removed, the child/adult is basically cured. Since the spleen is not there anymore, it also cannot kill the red blood cells. Once my daughter's spleen was removed, she gained so much more energy as the hemoglobin was actually getting to her cells, she actually HAD red blood cells, since several times she went into what is called aplastic crisis where her red blood cell production could not keep up with her spleen destroying them. That is why she can generate red blood cells now. Also, her bilirubin numbers started dropping (my daughter was constantly the color of a Oompa Loompa the first 8 1/2 years of her life). Before her surgeries pretty much every blood or body number that should be high, was low, and every number that should be low ,was high. Her poor body was so messed up. Every article about Shelby's condition that I have read sounded similar. I am sure that Shelby still has to be checked every year or so, especially to make sure that an accessory spleen did not grow (my daughter actually had another small spleen, along with the "normal" one which was several times larger than most people's spleens) so they removed them both. Her blood numbers need to be checked periodically also, and I would assume that she was probably prophylactically put on antibiotics also for a long period of time, since her body does not have the protection of the spleen, which in most people is a positive organ, but in people with spherocytosis is "evil". :) For example, my daughter takes antibiotics twice a day since she had her splenectomy, and probably will until at least age 21, since she does not have that protection anymore. She is at risk for bacterial infections and a high risk for sepsis if she gets any type of fever. She is also on folic acid to boost her body's ability to produce and maintain new cells. Red blood cell formation is dependent upon adequate levels of this vitamin. My daughter has been on folic acid since age 2 when she was diagnosed with this hereditary blood disorder. Shelby is not messing with the system or blood doping, etc. If her journey has been the same as my daughter's, which it sounds like it has, she is "cured" now of the anemia without the spleen, and that is why she can set records and compete at such a high level.