I know how hard that is, and even more so when people around you don't believe you, but you don't need their approval, it's not an imaginary disease, it's real, you smell, i smell, we all smell, but if you need to some money to the side to be able to afford a bit of medicine, a bottle of 200 softgels cost about 30 dollars, that can last you at least 3 months !
try to ask a good friend or a neigbhor to help you convince your parents, that's the hardest part, once they trust you, they'll help you and everything will become clear for them too.
My father trusts me, he helped me and still does, i'm not sure i couldn't do it alone.
Also, try to run at least 30 minutes a day, get yourself a standing desk, try tu cut out on some stuff in your food, sugar/dairy/gluten
If you find THE thing that make you smell, you'll be cured in 6 months maximum. 6 months of your life for a lifetime of happiness, it's worth it !