Mood changes on elvanse 50mg

I have been taking these for nearly 2 months now, and after about 6 weeks i have noticed once i take them, for about 3 hours after i feel fine. All good, but then i seem to take a nose dive almost instantly. I become almost depressive and angry. I feel anxious and just all around horrible in general. I can only describe it as feeling dissociated from myself and unrecognisable. I have been fine up until now?

Oh and i just want to add that around 7 in the evening i seem to come back to real life. Almost like once the medication is through my system im okay.

I feel very disheartened about this because the medication was really making a positive difference to my life and now it seems to have taken a 180 and makes my life much more difficult :/

Does anyone have similar experiences or could explain why this is happening?