EBF baby getting constipated???

I know sometimes EBF babies don’t poop everyday and it’s not likely for them to get constipated, but here’s the situation. Every couple of days for the past three weeks, my daughter has missed her daily poop. She is normal for a few days but then has a day where she’s straining all day, her stomach is hard as a rock and gurgling, and she’s incredibly fussy. The doctor told me to give her half of a suppository and that was it. When I did she went and it looked normal except for filling up three diapers! The next time it happened a few days later, after hours of her screaming, I tried the suppository again and she felt tons better. The doctor isn’t telling me anything is wrong but why do they keep recommending giving my daughter a suppository when there must be some underlying issue if she cant poop?? My motherly instincts don’t feel right about it, but I also don’t want to seem too paranoid being a first time mom.