Suggest Treatment For Vagus Nerve Damage, Low Blood Ferritin And Vitamin D Levels

Hi. My mother has ongoing issues with low blood ferritin levels (currently 22) and has recently also shown low blood vitamin D levels (in spite of frequent outdoor activity, they recently came back at the bottom of the insufficient range). She also has bowel issues related to vargas nerve damage. Her doctors are at a loss to explain her low ferritin levels. She has been taking iron supplements with some improvement, but it aggravates her bowel issues. Is there anything else we could/should be looking for? She has undergone many tests over the last 5 years, and is currently under the care of several doctors (general MD, nutritionist, and a hematologist/oncologist for her blood level issues) to try and manage her symptoms. But that s all that they seem to be doing...managing her symptoms. I feel that there is something more going on that her doctors are missing, if only because they hadn t thought to look. I m hoping you help by providing a different perspective and perhaps suggest something we should be having her doctors look for. Thank you for your time.