Nosebleeds can be caused by really dry weather of any temperature. Your symptoms may be unrelated, but since they happened simultaneously, we'll assume they're related. Depending on the amount of blood loss, that can cause dizziness. Since your symptoms are so broad, it's hard to know for sure. What were you doing during when the nosebleeds started. I sometimes get these symptoms, sans nosebleeds if I haven't eaten for a while, or if I go from light activity to heavy activity. I might try taking Acetaminophen or Ibuprofen to help with the headaches, but be careful and ASK FIRST. Overall, it probably isn't to serious and may get better on it's own. If symptoms persist, seek the help of your guardian and doctor. Hope you start feeling better.