I'm not very familiar with SD, but I've heard Accutane can cause hair loss. You should try to use castor oil cut with olive oil and massage it on your scalp at least 3 times a week. It's enough to leave it on for one hour or so. Wash it with a shampoo that doesn't contain any sulfates, as it is a well known skin irritant and is the very culprit to many scalp problems.
I'm using an old fashion shampoo bar ( solid) made with wonderful, soothing oils, no fragrance. Check out JR Ligett or Chagrin Valley, both wonderful products that are nurturing and wholesome to our fragile hairs. Rinse with a white vinegar mixed with warm water, ratio 1:9, but just see which ratio works best for your hair. I have found that ACV leaves the hair feeling greasy due to it's residue that gives it it's color, but the white vinegar leaves my hair shiny and silky smooth. And yes, it is needed after a wash with a shampoo bar since it's quite alkaline and opens up the hairshafts outer layer, making it dry and rough feeling. The acid closes them up right away.
Anyhow, castor oil is a miracle oil, it can penetrate deep into the tissues and it does stimulate the hair growth, waking up dormant follicles. It's a well known trick since far back in time to get thicker hair.it's also anti-inflammatory and anti fungal. And some think that Demodex skin mites are the cause for many scalp issues which will suffocate and die from the oil.
Make sure to change your pillowcase very often as well as your bath towels. Disinfect your combs. And give your scalp a deep tissue massage for about ten or more minutes a day. Never scratch your scalp, germs from under your nails can get under the skin and you'll pull out hairs/break them off. I know it's hard, but wear boxing gloves if you must, lol
Build up/excessive scalp oli can also very well be due to harsh chemicals in commercial shampoos, as they strip the scalp off all and any oils so the scalp only produces more and more. Then it's also a hormonal issue that tends to get less with age. Start tajpke OTC Saw Palmetto every day that helps reduce the amount of dht build up in the follicles that's the main cause of hair loss.
You could still be suffering from mpb, regardless of how the rest of your family look like. But, it doesn't have to progress to severe baldness and there's a lot to do to slow it down. Check out the Hairmax laser comb online, it's FDA approved and have a high sucessrate in regrowing hair and tons of happy customer. Hair follicles loves light therapy.