It's strange to see that its starting come out so quickly. With male pattern baldness it generally comes over a longer period of time. Think hard, has anything changed in your life thats pretty major in the last few months? Have you started taking other medications? I would go with Mrjb on this and go and see a dermatologist. With regards to your diet, I would recommend going on a good diet making sure you get all the essential nutrients, b-vitamins etc. You will not know whether the vitaimins are doing you good yet, give it at least 3 weeks or so. Its no good just having vitamins while you carry on having a poor diet, get some good quality natural food down you. You can also try exercising more as this can't hurt.
Hope that helps
Jason