I'm so sorry your DD is going through this. It is so hard.
I've had 2 rounds of accutane and would prefer never to do it again, though very effective. 7 years apart. Don't regret them but side effects are a lot to cope with. Had great skin in between. I'd not bother with pantothentic acid if you are at roaccutane stage personallly. A good multivitamin though with vitamin d. I take prenatal vitamins all the time because of how much more they have in them for skin issues.
Are you in the UK? GP can prescribe adapalene - which is retin A. Use this every 3rd day then every 2nd then every day at night and wear high factor sunscreen! It'll take about 2 months to see the full affect but honestly it does work! Worse before better as it brings everything to a head. It is a topical form of accutane in a smaller dose so not the same side effects.
To wash face use aveeno cream (not the lotion) rub all over face in circular motions then use a warm/wet clean cloth to remove what's left - circular motions. Nothing else!
Spot prone skin is sensitive skin. A blocked pore is a blocked lore but an irritated blocked pore becomes a spot. Don't irritate it by picking, poking, gels and creams.
I've had years of acne hell then someone eventually said to me, oil and water don't mix. Oil breaks down oil. Oil is your problem, use oil to break it down. Aveeno does this gently.
My skin is fantastic on this regimen and wish I'd done this before I did second round of roaccutane. That said, hopefully this will get you through until you can start roaccutane at least.
Also. Stress hormones ramp all this up even more. Daily exercise / movement really helped me too. Good luck 😉