Are there any supplements recommended for vegans who fall sick often?
I am a vegetarian myself. The vegan lifestyle is environmentally friendly and possibly healthier, but there are many potential pitfalls. If you are not bound by religion or otherwise, it might be good to still eat small amounts of animal based products once a week to stay healthy.
Otherwise, you might need to supplement your diet with iron, B12 and folate which are missing in a plant only diet. Your best bet is actually to join a community or a forum where there are other people with your same eating habits to ask for advice.