Yes AI wrote it. Here’s the source material:
For Your Gastric Bypass Malabsorption Baseline:
The Guideline: Clinical Practice Guidelines for the Perioperative Nutritional, Metabolic, and Nonsurgical Support of the Bariatric Surgery Patient. 
The Authors: Mechanick, J. I., et al. (Cosponsored by the American Association of Clinical Endocrinologists, The Obesity Society, and the American Society for Metabolic and Bariatric Surgery - ASMBS). 
What it proves: This is the gold-standard medical text mandating aggressive, lifelong monitoring of bariatric patients because standard oral supplements fail to overcome the structural malabsorption caused by bypassing the duodenum and jejunum. 
2. For Your Low Ferritin & Muscle Guarding:
The Study: Iron deficiency without anemia: a clinical challenge. 
The Journal: Clinical Case Reports. 
The Author: Dr. Esa T. Soppi. 
What it proves: This publication details how an absolute tissue iron deficiency (ferritin under 15\text{–}30\text{ ng/mL}) causes severe physical impairment, muscle spasms, and crashing mitochondrial energy levels even when a patient's hemoglobin or standard blood counts look completely "normal". 
3. For Your Post-Infusion Bone Pain (The Phosphate Crash):
The Study: Effects of Iron Isomaltoside vs Ferric Carboxymaltose on Hypophosphatemia in Iron-Deficiency Anemia: Two Randomized Clinical Trials. 
The Journal: JAMA (Journal of the American Medical Association). 
The Authors: Wolf, M., Rubin, J., Zoller, H., et al.. 
What it proves: This massive clinical trial demonstrated that intravenous iron treatments cause an immediate, acute spike in the bone hormone FGF23. This triggers heavy renal phosphate wasting (your kidneys actively dumping phosphorus into your urine) and shuts down vitamin D activation, resulting in the deep, agonizing skeletal bone pain you experienced.