mood swing and drugs

so i have been taking 150mg of venlafaxine daily for just short of a year now and some things i have found do trouble me, if i forget to take the tablet then my mood swings right into aggressive and almost violent, until i remember that i have not taken the medication then after about 15 mins a wash of calm goes over me is this normal?
this medication has helped me it has reduced the day to day headache but if something triggers an attack then all plans are off basically, i have tried other drugs but had some bad reactions to some and nothing happens with others but wonder if there is a better drug out there that could better for me?

There is only one way to find out and that is by trial and error.