your current weight and height are no obstacle to undergoing a water-only-fast, and given your symptoms this can only help to resolve your health-issues, although a low-fat high carb diet is not ideal. Fats are essential for health and why they are known as Essential Fatty Acids.
A low fat diet is a mistake made by many, and esp' vegans.
................that includes omega 3's either from supplementation or from oily fish such as wild caught salmon/tuna. If you are vegan/vegetarian, then a combination of a good quality flax-seed oil (Barleans) mixed with a sulfurated protein is the very best (Budwig Protocol). The latter has been known to cure many a health malady permanently and not just cancers. The Budwig protocol includes sunbathing for Vitamin D production, of which most of us are deficient (very deficient)............ http://www.healingcancernaturally.com/budwig_protocol.html
If your appetite was poor or non-existent I would recommend a fast, but after the above protocol for a couple of months, I would then undergo a water-only fast for at least 15 days to establish a permanent cure.
We should also bear in mind that fasting is a state of nutrition which aids the body in self-healing, but if you supply your body with the nutrients it needs first and foremost, this will greatly assist your body in achieving true wellness.
My own guess, is that your Vitamin D and essential fatty acid status is deficient, so all of the above should resolve your health-problems.