Cluster feeding

We started last night and have went all day. I just fed him for 12 minutes and now he's hungry SCREAMING again!!! How long will this last??? I'm exhausted and I stink and my boobs hurt and I'm going CRAZY HERE!!! We have a peds appt on Friday but at this rate that seems SO FAR AWAY...how long is the cluster feeding normal with an EBF baby and is it normal at 8weeks? That seems a bit late as I was told to expect it at 6 weeks. He's advanced in every other area so idk why he would be late on this.