I was going to recommend Joey’s “how I healed my teeth with sugar” book, but Joey beat me to it!! :)
Also – load up on Vitamin D. You need D to be able to use calcium and rebuild enamel…. then load up on calories and nutritious foods, so your body has the energy and raw materials to get to work on fixing stuff up.
You might also find a probiotic/enzyme supplement helpful, if your gut is having issues with digestion.