What Causes Fainting And Headaches?

hello, i've been ill for quite a while now and im going to the doctors on tuesday but i want an answer before i go. I've fainted about 2/3 months back and since then i have been on and off feeling faint and getting nauseous all the time, i get mild headaces around the temple area and pills wont take it away, i also get pains in my right side just below my rib cage and when i breathe sometimes it feels like when i breathe deeply on a cold day. could you help please? :)