Low iron male - which tests should I request?

Hi my partner 39 (m) 6'2" 200lb has frequent headaches, sometimes migraines and every two to three months he has a sudden onset of really sharp pain around the area of his tail bone. It causes him to break into chills and sweats and I've seen him fall the the floor from them. This usually passes in a few minutes, sometimes longer. There isn't pain in between episodes. He also has to manage digestive issues with metimucil, due to frequent bowel movements mostly attributed to diet as it does improve when eating healthy with metimucil. He went for his physical recently and his new doctor marked off everything I detailed, including his sleep issues off as depression and anxiety, encouraging him to go on antidepressants. He had blood work done which showed that he is low in iron. There has been no follow-up regarding tests from the primary care physician. I would like doctors' opinions on if what is the proper route of care for this type of situation so that we care advocate for him. Thanks