when was the last time in 10/2104 that patient 14990 was prescribed with lisinopril and potassium chloride 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 = 'lisinopril' and admissions.subject_id = 14990 and strftime('%y-%m',prescriptions.startdate) = '2104-10' ) as t1 join ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'potassium chloride' and admissions.subject_id = 14990 and strftime('%y-%m',prescriptions.startdate) = '2104-10' ) as t2 on t1.subject_id = t2.subject_id where datetime(t1.startdate) = datetime(t2.startdate) order by t1.startdate desc limit 1