when was the last time since 04/2104 that patient 88659 was prescribed vial and iso-osmotic dextrose at the same time?
select t1.startdate from ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'vial' and admissions.subject_id = 88659 and strftime('%y-%m',prescriptions.startdate) >= '2104-04' ) as t1 join ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'iso-osmotic dextrose' and admissions.subject_id = 88659 and strftime('%y-%m',prescriptions.startdate) >= '2104-04' ) as t2 on t1.subject_id = t2.subject_id where datetime(t1.startdate) = datetime(t2.startdate) order by t1.startdate desc limit 1