I am very concerned with the bowel movements my 12 month old son ...

I am very concerned with the bowel movements my 12 month old son has had. It even smells like blood. He has had four already. He has no appetite for table food and is barely drinking the bottle. He has been fussy and has not been playing the way he normally does. I called the nurse line and they said I definately need to call his doctor in the morning and take in the diaper to have it tested for blood. She said not to wake him up or take him to the er, though. I should have called yesterday, but I didn't know if it was a normal side effect or something to do with the iron supplement he just started. This is his 7th day on the meds. Now that I think back, he hasn't eaten well since the 4th day of antibiotic. I will call the doctor in the morning, especially since the comments on this site are mixed.