Melasma and freckles are gradually appearing.

Literally, freckles and blemishes

I am seeing a lot of progressive dark spots and blemishes appearing. I always apply sunscreen and BB cushion foundation, but I can't avoid UV rays completely. When I do, my skin tone gets increasingly uneven. The dark spots used to be small, but they are growing larger and fading, with new ones appearing right next to them. It is really upsetting. What should I do in this situation?

What is the cause of melasma and freckles that keep appearing?