It seems to be a fungal infection in your left armpit. I suggest you see a dermatologist to look into the rash, and get a medication accordingly. Deodorant should also be avoided as it might make the situation worse.
 

A ringworm is a skin infection that is caused by a fungus. It might make your skin itch, become red, or get scaly. The most successful treatment for ringworm is an antifungal cream which you can apply to the area it is affected. A prescription is not necessary when buying these creams at the pharmacy. Don´t forget to clean the site and keep it dry to get the best result.

Pigmentation is triggered by different factors such as genetics, sun exposure, and hormonal changes. A balanced diet rich in antioxidants and drinking a lot of water may help improve skin health. You should consult a dermatologist for proper diagnosis and treatment. They may prescribe an appropriate medication and recommend certain lifestyle changes to control pigmentation.
 

You must visit a dermatologist first. You may try using natural remedies such as topical applications of lemon juice, almond oil, and aloe vera gel to help reduce the appearance of the black spots on face. Also practice good skin care habits such as avoiding harsh soaps, using sunscreen, and avoiding excessive sun exposure.

From your description, it does sound like you may have rosacea. This condition can cause redness, flushing, and even changes in skin texture over time. Sometimes certain products or triggers can worsen it, as you've noticed. What I'd recommend is simplifying your skincare routine. Stick to gentle, fragrance-free products and avoid anything that could irritate your skin further. It might also help to identify and avoid triggers like spicy foods or extreme temperatures. If the current treatment isn't working. There are other options we can explore together. Let's work on finding a solution that suits your skin type and helps manage your rosacea effectively.