I'm still learning about it, and how to treat it, but what I have learned is that it's cystic acne. It can be caused by hormones, heat, moisture, ... No one seams to have the "cure", but I don know that lemon juice will lessen the dark appearance of the scars left behind.
I've been getting mine since I was 14 (puberty) so I'm fairly certain it's hormone related. Doc's have said it's b/c I'm overweight, but I've had it at 135, 160, 200... the same at any weight, so I know that's BS.
Sorry I can't be more helpful.