Too much sleepy. Or something else?

Hi doc, My daughter is 1month old , when I was discharged from hospital I was said to give vitamin D , multi vitamin and iron drops for her . Later wen I visited pediatrician I was said to stop iron drops .  is it ok to put iron drops ? Or should I stop it as per my pediatrician ?? It's about 15 days since  I stopped the iron drops  and for the past two three days my baby seems to be dull and sleeps all day long without having milk ,even though I force her my nipple she doesn't suck much . I breast feed my baby .I also feel she has dropped weight. Her birth weight was 2.5 and wen I lasted visited the doc it was 3.25 but now she looks like she has dropped weight. Am worried about this pls help me . Is the issue coz I stopped the drops or something else ?