6 Year Old On Methylphenidate For Last 3 Months For

6 year old on methylphenidate for last 3 months for ADD. It’s a 4 hour dose, so 3 x a day at 20 mg. Things improved in school and he got good reports. He did have mood swings here and there, but nothing too bad or too long. Dr. decided he may de better focusing and help with mood swings if they added Strattera at 10 mg for 5 days, and then 18 mg after that once a day. Was on for 17 days, and more irate and intense mood swings and very bad scared thoughts and anxiety at times. Called doctor and we took him off immediately. He’s been off 3 1/2 weeks now and still seeing him be very scared for awhile 45 mins. - 1 1/2 after each methylphenidate dose of medicine. Dr. said it could take a month to be totally out of system , but we’re not seeing any dissipation. Could it still be the straterra causing this, which he was never scared like this before, or the anger issues, or could it possibly be the methylphenidate?