Hi
Hope you are doing well. The symptoms described by you may be due to chronic skin infection (fungal or dermatitis) or may be due to hormonal imbalance. It would be difficult to diagnose without an examination.
One possibility is Polycystic ovary syndrome, a hormone imbalance condition that can cause irregular periods, unwanted hair growth and acne during adolescence and teenage. There could also be weight gain or trouble losing weight, patches of dark skin on the back of neck and other areas (called acanthosis nigricans) and mood swings. Many adolescent patients with PCOS have higher levels of the hormone insulin in their blood, which causes patches of darkened skin on the back of neck, under arms and in groin area.
I suggest it is better to seek a doctor’s opinion and a complete physical examination. The tests required may be blood test to check your hormone levels, blood sugar, and cholesterol as well as an ultrasound of your uterus and ovaries.
Do write in after your doctor’s consultation.
Take care
The thighs are probably yeast, a fungus that grows in moist areas. Monistat can help get rid of it. Use the cream and you can apply as often as necessay. I used it about 10 days to make sure I cleared it up. You can get a femine non allergic deodorant spray to help keep it dry from sweat. It is possible that is what is affecting the underarms, so you can try that and the same spray. It could be the deodorant you use also. RJ