This is a very complicated question for a forum like this. We can't know if there's some condition you have that might be inhibiting healing. We don't know what you healed like before the treatment. The disease has effects. Often when radiation treatment is complete someone involved in natural medicine might take supplements to boost the immune system, which is often adversely affected by radiation, but you can't do that because you have an autoimmune disorder and don't want to boost your immune system. Another thing they might do is take detoxification supplements to detox the liver, which can also sometimes be adversely affected by radiation. This can be done by eating foods, largely algae and certain sprouts, that are known to help with the toxicity radiation leaves behind. These are foods but because they are not tasty they are usually taken as juice or supplement form, such as wheat grass and spirulina. Most people would say a good quality multivitamin, and most aren't good quality, can be a helpful prophylactic, but won't be strong enough to do anything major. An herbalist might try to boost your adrenals with adaptogens, because the thyroid is intimately connected to the adrenals. Your profile says you're 22, and if that's so, the best medicine would be a very very good diet filled with antioxidant rich foods such as the algae and wheat grass mentioned (don't take seaweed, just fresh water, because seaweed is high in iodine and might not be good for your thyroid condition) and lots of colored veggies. Others might try a juicing diet for a time, again to clean out the system a bit but more because you can squeeze in more antioxidants by juicing than you can eat. But a caveat -- whenever you have a disease as you have and don't know a lot about this stuff, do a lot of reading first and you might want to see a professional in this type of medicine. The rest is up to your docs.