I too have had both sinusitis and nose bleeds for as long as I can remember. If mine are related, it would be because the symptoms of sinusitis (intense sneezing, runny nose) might irritate the membranes in my nasal passages and cause one of the capillaries to rupture, resulting in a bleed.
Unless you want to go get your nose cauterized (where and ENT doctor selectively burns areas of the inside of your nose to create a little scar tissue around the areas where you bleed--sounds worse than it is!), you can treat your nosebleeds by keeping the inside of your nose hydrated. Try a saline nasal spray and/or some coconut oil (or any other natural moisturizer you like). This is especially important during the winter, when indoor heat might dry up the air.