Scar tissue is a great possibility! It can prevent elasticity, thus preventing stretching in general.
The best way I know how to get rid of scar tissue is oil massaging. Many people say that emu oil helps to break down scar tissue, but if you're a vegetarian/vegan, you wouldn't want to use it. Emu oil, after all, is made from the fat of emu birds!
You can also use jojoba oil, or even castor oil! Castor oil is a wonderful oil with many healing benefits, and I use it when my ears become irritated. It really helps them calm them down and heal more quickly, as well as soften the skin and connective tissue that makes up the ear lobe. It also helps a lot with the lymphatic system; so if you experience a lot of lympatic fluid secreting from your fistulas, castor oil can help reduce that secretion!
If and when you decide to start oil massaging, it's best to make sure both your ears and hands are clean. Massage a little bit of oil into your lobes for a few minutes. I can fit in about five minutes per lobe while watching a video online; it helps to make the time pass more quickly, so you're not counting the seconds.
But whatever works!
EDIT
As far as trying to stretch the lobe up to 10g when it can't at the moment, I wouldn't suggest you force it. Obviously.
You'll just have to be patient with your lobe if you want healthy results, and that means waiting for a while longer. Patience is a definite citru (I meant to spell virtue! Not citru. lol I don't know how that happened!) within the ear stretching community!
