Any suppression issue was waived when it was not raised through a motion prior to trial starting in the justice/municipal court. There is no right to an attorney on a class C offense so your son should have either made it known that he wanted to hire one otherwise he gets stuck representing himself. If the trial was of record (there was a court reporter) then he can only appeal errors in the proceeding which means that he cannot raise the suppression issue now. If the trial court was not of record he can appeal and get an entirely new trial at the county court level and he could file a motion to suppress then. You only have 30 days to file your notice of appeal after he is sentenced. If that time has run then he is out of luck.