I'm sorry you're in this position but I can't help there's a lot more to this.
However, it is not normal for people to be uncontactable for 2 days. So, the company requesting you to have a medical check up is not unreasonable.
If you comply, they have no reason to sack you.
If you do not comply, you certainly don't help your position. Think of the situation from their side and put yourself in their place. What would you think?
Also, if you didn't touch the CD, how do you know porn was on it? You only have this other person's word - then you reported him for having porn? Did anyone check him for having the disk? Did they find it and check it?
Contacting all the media won't help if you only present half the facts.