Yes, you should be concerned. You say you've tried every diet, but that's probably not true as there are as many diets out there as there are people who eat food. You'll get better advice if you tell us what your weekly diet is like right now, because the way to lose weight and keep it off is to alter what you eat permanently, not go on a "diet" and increase your exercise. This should result in slow but lasting weight loss. Unless, of course, you have a health problem you're not stating that makes it harder for you to lose weight and easier to gain it.