Hemsi-PD & foul brown stool. Hemsi-pd?

Hello, My 5 month old baby girl was prescribed 0.5ml of Hemsi-PD iron. When I started giving her, she had foul smelling dark greenish brown stool with mucus. When checked with the paediatrician, I was asked to reduce the dose to 0.3ml as there shouldn't be any mucus in stool. I started giving 0.3ml but the issue persists. Her stool was the same foul smelling with mucus. When I stopped iron drops, the stool was back to normal, mustard yellow with no foul smell. Does this mean she's allergic to Hemsi-PD? We reduced the dose further to 0.2ml and now the stool is foul smelling greenish brown but no mucus. However, she has been pooping for 4-5 times than when not consumed. She's fussy while feeding. Her stomach is growling. We have checked it a couple of times, this happens only when we give iron. Kindly advise! Thank you!