I have a question about what could be causing nosebleeds?

For about the last two years I've had problems with infrequent nosebleeds. At the time I got the first one two years ago, it was quite a gusher. I wasn't doing anything out of the ordinary, just pulling weeds in the garden one late spring morning. Hadn't had a nose bleed in a long time since a kid. Ended up going to emergency to get it to stop. No idea why it happened. Happened again in a few days - made Dr. appt. after that. She asked all sorts of questions. I take vitamins, BC pills regularly. I had been taking a supplement for weight loss that I really liked at the time, also had been taking fish oil at the Opt. Dr. suggestion to combat dry eyes, had been taking Claritin for allergies. The dr. said it couldn't be any of those things and I shouldn't change anything but rather put vaseline in my nose at night to keep it from drying out (t had been quite dry) and use Nasacort at night. I did this for about a week without success - ended up with bloody vaseline all over my pillow in the morning. So I decided to quit all medicines except BC pills. The bloody noses went away soon after. I chalked it up to the caffeine in the diet pills and perhaps the dryness the Claritin seemed to cause. Haven't taken any of those since.

Come winter, I thought the dryness in the house would cause them to start again. They never did. It wasn't until late spring/early summer last year when the allergies start that I noticed dryness in eyes and nose that I seemed to have slight nose bleeds again but nothing to the extent like the year before. I started taking Honey grown locally in place of sugar to try to help the allergies and Magnesium to combat the allergies as well. The allergies subsided greatly and I've noticed when I run out of magnesium after maybe a week or so, the allergy symptoms come back en force. Last night I got quite the nose bleed again. Today it's coming and going. I can feel the back of my nasal passage get gooey.

The bleeding isn't coming from the nasal walls close to the surface - like right near the holes in my nose - I can put tissue there and there's no blood, but if I roll the tissue and put it in there to try to get rid of the goo (can't blow it, then it gushes) the tissue comes out soaked - it's like the blood is coming from WAY back in my nose somewhere.

I plan to get more magnesium tonite in hopes it will subside when I get taking it again - this will be the only change I'll make so if it gets better, I'll know it's related to my taking that magnesium.

But I'm still worried that it's being caused by something else - anyone got any experiences or ideas to share about it? Is there something else that can cause these that's dangerous? Is Magnesium dangerous if I take too much?

Ideas please and thank you for your time.