I am having exactly the same problem, although I received the astrazeneca vaccine. I have always had quite high iron, have given blood successfully for the past 10 years (but generally only once a year). I had the first AZ vaccination in January, then the next in April. I began suffering with headaches/ tiredness/ dizziness in February, but this got far worse in May/ June. I had a blood test in late June, had very low hemoglobin level and my ferritin was 2. I have been taking iron supplements since, no improvement in my blood as yet. Due to have another test next week, doing everything I can to increase my iron absorption! No idea if it is related to the vaccine or not, but I am generally very healthy, I am 31 and have no other health problems.