Anemia in Pregnancy

My hemoglobin levels came back around 10.2 at my appt. they told me I could get and iron supplement for prenatal health or switch to a different prenatal vitamin, well I got the iron pills & the last two days I took them I felt EXHAUSTED, not to where I could sleep but where I just layed around & done nothing & was in a bad mood , once I stopped taking them I felt “great” (I am 30 weeks pregnant) but so much better than I felt when I was on them & back to how I felt before. I’m not going to take them as I felt fine before it , has anyone else experienced this ?