Week 8 on Venlafaxine and still anxious :(

[Mindfullness]

I have been on Venlafaxine for 8 week's, 75mg. I still feel anxious, heart racing and so tired. Should it have worked by now. I also ache all over and feel like I have the worst hangover every morning.
Do I need an increase or is it not the right drug for me? Thank you