No clue about the medical bills, but as for the credit cards - they might not appear on Experian's report, but they might appear on another bureau's report (Transunion, Equifax).
Not all banks/credit cards issuers report to all credit bureaus. You can try asking them nicely to report to Experian if they don't, but I wouldn't count on it (though I've never tried it myself).
You could pull the report from Transunion and/or Equifax to compare the information they have, which you can do once a year for free (as you probably know by now).
Also, you can try registering for creditkarma.com to see what information Transunion and Equifax have on you - the credit score they give is not your "real" credit score (that doesn't exactly exist even... but that's a whole other discussion), but you should be able to see what credit cards they have on file for you.