You say you are self employed so it sounds like you have submitted a false Form 11 i.e. all income was not returned on it.
The correct thing is to self correct your returns and pay the PRSI. To do this, you need to write to Revenue and inform them that you mistakely ommitted interest income in your returns and could they amend and send you corrected notice of assessments.
When you get the assessments, revenue may also have applied interest or penalties. Revenue can by concession waive penalties but never the interest. If applied, I would ring them and see if they would remove the penalty charge.
Pay the balance quickly and hopefully it all won't trigger a Revenue audit.