The dosage of your milk thistle product sounds to me very odd. 1.000 mg - of what.
As you may know, the active ingrediences of milk thistle are silymarins. Any reasonable thilk thistle porduc should have an information on the label that informs about the strenght of the silymarins.
I highly suspect that the M.T. product you took is not the best under the roof. By no means milk thistle should induce these unwanted effects you had. On the contrary, most people get more alert and feel a lot better even after a few days.