One other thing, vegan doesn't support any animal protein at all, but I recommend eggs so long as there is not a known allergen to it and thought I should tell you that if you look into it. I use organic eggs and get good protein from them, fried in coconut oil with fresh garlic, green peppers and onions is really great and good to the body. Also peanut butter or almond butter or any of the nut butters without any added sugars. The almond butter is by far the best of all of them. Start to slowly take him off things and then re-intro to get a better idea of what in his diet his body is not liking. Sometimes it is easy to start with removing dairy first, it is usually a huge culprit in the scheme of things. It should take a good three to four weeks before you see any real difference and he may experience some low points where he craves the particular food that is normal but not to give in to it as it passes. Common things to look into are wheat/gluten, dairy, meats, definitely sugar of the white sort!! Organic sugar is a good alternative and is very very good, much better than white sugar!!! Carob in place of chocolate too....be careful of soy milk though as it has a thickener in it that could cause trouble...otherwise any other soy products are great. There are many vegan products on the market besides fresh fruits and veggies that are really good...let me see,the Tequitas....not sure the brand but they have pinto beans and soy in them, all organic with organic corn toritlla wraps, very good...I'm thinking this age he is at is a very tough one for food so it may take some time to acclimate him to a new style of eating but I am certain this will help him feel so much better. Homemade ginger bread/cake is an excellent source of nutrition and a good treat so long as you use blackstrap molasses to make them. The thing with Lupus is it takes extra effort in these areas but at some point it becomes very simple because it's a way of life you adopt....and it is well worth it.
Looking forward to hear more about how Mike is doing. Take care and him too. ;-)