Help! Does chlorella cause skin rashes?

I've been taking chlorella for the past week, and I've noticed I've developed hives, not very dark yet but definitely itchy, all over my face. I wanted to take chlorella to detox heavy metals. I'm pretty sure I've got mercury poisoning, considering I have basically been living on tuna (I am 26 and female, by the way). Does chlorella cause this? Could it be just a temporary detox side effect?

I keep hearing different opinions about it. Some people say it's a miracle food; others say it's terrible for you, especially if you are high in sulfur. What is that, and how do you know if you are high in sulfur?? Please help. I'm not sure if I should stop talking it, or if maybe something else is causing these hives.