Substantial delay in litigation may occur as a result of a conflict of interest unless prompt efforts are made to discover any such conflicts. A lawyer should take all reasonable measures to determine whether or not a conflict of interest exists under Rule 1.7, 1.8, 1.9 or 1.10 before undertaking representation. If facts which would lead one to believe a conflict of interest exists come to the attention of the lawyer after representation has begun, the lawyer should determine whether a conflict does exist with all reasonable diligence.