I'm taking Floradix now and there is a child dose for it but not a child version of it. He still might not like it, though. It's better tasting than other iron supplements but still has a bit of a taste to it. It doesn't cause constipation or anything.
If his iron is slightly low, it's likely normal. Even if he's eating well, he might not be getting enough iron (a lot comes from beef and green foods, especially spinach). I've known lots of little kids that show low iron levels around that age. Not that it's normal to have it slightly low - just somewhat common.
My daughter is severely anemic, but it has nothing to do with iron. Her body just won't make enough red blood (or platelets or white blood cells). She actually needs a bone marrow transplant.
If your son has something seriously wrong, often the blood counts will get worse or something. If it's just slightly low, it's probably pretty okay and hopefully diet can fix it. You might want to try giving him the Floradix in a little smoothie of something to see if you can mask the flavor! :-)
Sorry you're having a hard time with this! Oh, and my 14 month old eats whatever we eat. Apples, bananas, various chicken, ground beef meals...not too much into salads;-) I have no idea what her iron levels are. But I remember my 11 month old had hemoglobin levels down to 10.
I think the Floradix said it was 1 tsp per day for a child 6-12 years old. Maybe you can ask your doctor, but I would guess that 1/2 tsp a day for a child younger would be safe. The worry of more would be iron overload. But it sounds like he needs the iron.
Good luck figuring it out!