My Father Is Currently In The Hospital. He Started Having

My father is currently in the hospital. He started having nose bleeds this a.m. and my mom took him to an IC facility in our town where they packed his nose and then stopped the bleeding and sent him home. Approx 2 p.m. his nose started bleeding again and they went to area ER. He was just admitted because they can't seem to keep his nose from bleeding once the packing is out. His BP increases and goes too high when his nose is packed. Once they unpack his nose, his BP falls but his nose starts to bleed again. BP is down now and he is being observed overnight. He was told his membraines were dry but I'm curious it could be something else. Not sure if there has been a sinus ct or not. He is 82 years old and in great health. Any ideas what it could be or the cause?