What are the chances of Lead poisoning in the blood?

I have come in contact with this sheets of Lead from the hardware and I melted it in open fire (for 5 hours or so)without any protective mask for my nose except for a handkerchief. It was for my materials class for sculpture. I think i'm having irregularities lately... What are the signs of being poisoned with this metal?

Additional Details

it was already 4 years ago and my mental health is not good lately.
ok thanks. i will do that. oh go get a lead test at the hospital do not mess with any more lead. Best is..... consult a doctor ASAP.... you need pro help to make sure... i don't think you can really rely on yahoo answer..