Sometimes this gets so frustrating

So it seems like every time I lose a few pounds I gain it back within a couple of days.  I'm still seeing progress on the weight loss but it is so slow.  So I was so excited to finally break through my 2 week plateau only to find frustration once again. I went down 3 lbs but gained 2 back in a matter of a day.  I really didn't do anything different except eat a sweet treat late at night and a couple of grapes but that shouldn't put the weight back on.  I'm trying hard to reach my goals.  I'm doing pretty good so far but this weight gain can be so frustrating.  I guess I shouldn't be terribly upset but I want to make more progress than 1 lb in 2 weeks.  So my weight is at 303.  The next goal is to get down to 284 by the end of september.  Heck I would take just getting under 300 by then.