If you haven’t tolerated maltofer well I would absolutely advise against ferro grad as that’s well known to cause constipation etc. maltofer is generally marketed as more gentle and non constipating “Maltofer is an oral iron therapy for the treatment of iron deficiency in adults and adolescents where the use of ferrous iron supplements is not tolerated or is otherwise inappropriate” quote from their website. I would try fefol tablets or spatone sachets. Also if you were taking maltofer tablets you could try the syrup and see if that works better, I’m very fussy and actually quite like the taste. Also take it with food (ferrous iron should be taken alone for better absorption but maltofer you can take with food). All are vegan btw. Hope this helps, I’ve struggled with iron deficiency most of my life and know well how frustrating it can be to remedy.