Having a bloody nose isn't uncommon, but when it persists for months, you need medical attention. A bloody nose can be a symptom of a much larger problem.
your blood cells
Red blood cells
every six months
Most blood centers allow for donating whole blood every 56 days (which is less than 3 months).
No it is fine to only get your period every few months. It is normal everybody is different it depends on your genes. If you have a problem you should go see your doctor but any other way it's NORMAL.
It is if you have serious problem with your teeth you go the to get treatment on them. (I go once every 3 months)
There is a great magazine called Runner's World or Running magazine and they have lists every three months on the best running shoes for different kinds of running, including trail running, track running and sprinting.
12 months
Yes, your body is constantly reproducing red blood cells are they only live for 3-4 months.
Yes, go to the doctor and he will tell you what to do next. Spitting blood is a problem.
Replace Heater Core
It takes the marrow about that long to fully replace the blood. Donating too frequently will result in your blood being depleted in several important components.