Why do i sweat so much and when i don't why do i smell so bad?

I am not sure if this is the right place to ask this question.
Recently (about 2 weeks ago) i started to gain weight. After that i started to smell very bad. I only gained about 3 kilograms max. I never used to smell and i never ever used deodorant only perfume but now i have to use both and even that doesn't let the smell escape. And i have been sweating alot on my back for the very first time today. I am in shock because i haven't got a clue what is going on with me. I am thinking of going to the doctors but i am also thinking its because of growing up. I am 17 years old and in about 7 months will be 18. I'm too embarrassed to hug or hang out with my friends. They say i don't smell but i can smell myself. Please help me. Thanks.

[JasonHB]

I used to sweat under my armpits when I was going into puberty and I started using Old Spice deodorant and it helped me get rid of the smell and sweat. You should try different deodorants and see which one is best for you.

Best of luck.

[Bhupinder Kaur, MD]

Hello,
Bad odor is mostly of sweat which may be seen in anxiety,obesity, allergies, eczema, psoriasis, synthetic fibers and warm temperatures. It is also seen in excessive sweating or hyperhydrosis. It may be as part of an underlying condition like Hyperthyroidism or similar endocrine diseases and dermatological conditions like eczema, psoriasis.

I think getting a thyroid profile tested in the lab may help and also please consult a dermatologist to find out the confirmatory diagnosis as treatment depends on the same.

I hope it helps. Take care and please do keep me posted in case you have any additional doubts. Kind regards.