I suspect it'll come out that it was a complication of taking something supposedly safe for his ADD, Many-itis, or some such nonsense.
Thanks for update above, Edit:
"Ramirez released the following statement Thursday morning: ?Recently I saw a physician for a personal health issue. He gave me a medication, not a steroid, which he thought was okay to give me. Unfortunately, the medication was banned under our drug policy. Under the policy that mistake is now my responsibility. I have been advised not to say anything more for now. I do want to say one other thing; I?ve taken and passed about 15 drug tests over the past five seasons."
of course.