Suggest Remedy For Significant Hair Loss

Hello for the past 2 weeks I have been noticing significant hair loss... a lot more than usual. Headaches... bruising very easily, tired all the time, and just not feeling "well." I know my body well enough to know something is not right. Also Im not sure if this is correlated but I have had this chronic stabbing pain in the middle right part of my back that comes and goes. Im not on any medications, not really stressed, I have started taking a multivitamin about 2 weeks ago (one a day) and have started to watch what I eat. Im 26 years old and weigh 120lbs and 5'2