HI there - I feel for your friend. I have been a sufferer of s imilar condition since I was 14, I am now 33. Maybe this will help.
My condition is called Hidradenitis Suppurativa or HS Disease for short. If you google it you will see. The name of the condition translates to inflamed swear glands. This is where the glands fill up with a solid (turning into abscess) and liquid state puss. It is very painful and often un-noticed by others due to position on body (arm pits, leg pits, bum, behind the knee, back of neck, under bosom etc). It can often release a foul smelling liquid and sometimes not heal for ages, constantly leaking.
I have not yet found any treatment that stop or even reduce this condition.
The many doctors I have seen always blammed it on acne. It took a very long time for a correct diagnosis to be made.
I do hope that you find an answer to help your friend, I have written about this condition on here before but I didn't get any replies. So I will be watchinhg this thread for a few days to see if anyone can help.
Let your friend have a read up on HS disease. If it is the condition they have, then at least you now have a correct name for it.
All the best and good luck.
BO.