Epsom Salt bath is effective. The first time I did it I used 2 cups in the tub and then felt like I was jumping out of my skin. I suggest starting with 1/2 cup per bath and "working up" to a larger amount. Your body will "get used to" eliminating this way. Saunas are also good.
If your boyfriend cannot smell this odor, and it is not in your clothes, it is entirely possible that the odor is in your sinuses or mouth or somewhere where your nose is picking it up but it is not actually on your body.
Have you seen a doctor or someone about this? Don't know if it would help or not, but they could possibly really tell if the smell were coming from your skin or not.
If it is coming from your "head" like in your sinuses, it could be just a chronic sinus infection or something. My mouth tastes metallic when I have post nasal drip. Other people get other tastes. Does this "smell" affect how food tastes to you?
One easy way to clean out sinuses - buy some whole organic ginger (from produce, not in a bottle) and put a thin slice or two between your cheek and gum on either side and the fumes created over the day will start making the stuff in the sinuses come out. Try to blow your nose frequently as it's much better for the stuff to come out rather than have it go down your throat and be swallowed.