Your supply can sometimes drop a bit during your period that’s the only thing I can think of
Totally normal it’s due to hormone fluctuations which changed the taste and quantity of your milk. I had this with my first and my cycle has just come back this time too. If you track your cycle you’ll notice it can happen when you ovulate too. Watch out for breastfeeding aversion because it a real thing and it’s awful. I soldier through mine but magnesium supplements help and distracting yourself x
When I was EBF this would happen with my little one, sometimes your supply can dip a little when on your period so it might be frustrating him that it’s not like a normal feed he’s used too! Keep hydrated and offering as much as he would like during this time x