I quit my last job for several months and I am looking for a new job recently. The recruit agency said the potential employer will give me the offer until receipt the reference check respond by my last job.

The agency said that they experienced a case that my last company hasn't responded for 3 months for other candidate.  If under this situation, what I can do.

Moreover, will my last job comment my performance to new employee?  I haven't done the appraisal review before I left.  I just concern whether my last boss gives me negative comment.