if all the fasting, cleansing and supplementation isn't helping, consider trying one of the energy meridian techniques. Skin issues be symptoms of stagnant liver/gallbladder and/or lung/large intestine channels. These may be affected by toxins, but emotional stresses etc or heredity (which can nevertheless be addressed) may also be underlying. Acupuncture can be powerful, or you can try to learn Jin Shin Jyutsu, which works based on the same principles but you can do it on yourself. You just place hands over Energy Locks along the pathways where energy is stuck, somewhat like a jumpercable.It is simple yet powerful. I work with this a lot, in addition to nutrition etc., and it is amazing. You can get books, see a practitioner, or join a class- they're available in many countries. It would be very useful to find a TCM person who can do a pulse diagnosis to find out what is going on-where is the deficiency/overload etc -which organ meridian is affected. Then get the book or class and work on yourself every day. As you say you're skinny and there is lots of dryness, I would suspect liver is involved-emaciation and skin dryness are telltale symptoms. To help the liver channel, you can try this:
With your left hand, hold the left occiput (base of skull)
With your right hand, hold under right center collarbone.
Reverse. Hold for a few minutes each time.
The middle finger relates to liver/gallbladder, and you can practice holding fingers-an ancient healing art, like the buddhist mudras.
Palming the calves daily for 20 minutes can also help skin issues. Ideally ask someone else to do it for you.
Another skin treatment is:
With right hand, hold right side little toe. With left hand, hold right sole of foot.
Reverse for left foot. Hold a few minutes each time.This harmonises kidney/bladder channel.
Also ask yourself if you have any emotions you need to release, such as suppressed anger/frustration etc. You can use EFT for this.
If this sounds too simple: In my last class, I met a 60+ year old man who had reversed his rheumatoid arthritis using JSJ and nutrition-after 40 years of suffering.
You always need hardware, software, and power to run the machine....
If you are interested I can send you more suggestions