What Causes Nosebleeds,severe Headache,hair Loss And Memory Loss?

hi for the last week i keep getting nosebleeds, have a bad headache just above my right eye, and have had hair loss asa result i now have a bald patch about the size of a 10 pence piece. i have been suffering from short term memory loss and occasionally get really bad pressure on the back of my head also having problems with my temper and feel angry all the time im really worried that something is seriously wrong with me can you help, do you know what this could be i am normally in good health and lead an active lifestyle im 27years old, thanks.