In the week before my period, i tend to get clumsier and less coordinated - bumping into things, stubbing my toe, dropping things, etc. not like that the rest of the month. is there a scientific explanation for why it happens right before my period?

In the premenstrual period hormonal changes cause fluid retention including in the brain which can cause many symptoms including personality changes. I have prescribed a mild diuretic in the week before the period to prevent such changes and symptoms. If you take a diuretic also take a potassium supplement with it unless it's a potassium sparing one. Discuss this with your MD.