Weight Plateau

So for the last year or so I have my weight has fluctuated from 170 to 160.  This Sunday I weighed in at 160 and this morning I weighted in at 163.  :( GRRR. I have been eating pretty good and exercising 4 or more times a week for the last 3 weeks and I keep losing and gaining weight within 170 and 160.  I am so sick of these numbers! I think I just need to be more stricket on what I put into my body and drink a lot of more water.