I'd suggest speaking first with the attorney who handled your closing for you. If they can not assist you with resolution of this issue (which it sounds like might have been anticipate-able when you closed on your unit), then you should ask them for a referral for an attorney who handles real estate litigation.
To clarify the language a little bit, I think that your concern should be with any common elements or limited common elements of the condominium that might have been altered by the previous owner. If you now own the unit, then you own their alterations to the common and limited common elements (and thus may be compelled to pay to correct them).
Let me know if you need any additional assistance or referrals for real estate litigators.
Broker Associate, Sudler Sothebyâ€™s International Realty
3934 N. Lincoln Ave. Chicago, IL 60613
773-418-0640 (mobile) 312-577-0985 (fax) 773-293-1200 (off)