I would ask for a referral to an ENT specialist and some routine blood tests such as iron like you mentioned, Hb, platelets, thyroid, liver functions. Basically the standard ones. My daughter had similar symptoms. It turned out she had low platelets which was due to recurrent infection. This would vary from tonsilitis to school sores etc. Her immunity was very low. All her problems the ENT believe is from her tonsils. They are grade 4 even when not infected. They are coming out shortly (couldn't have them out when her platelets were so low).