sudden weight gain since last month...

Hi,
I am a 27 year old male from delhi, my weight was 65 kgs, but since last 1 month, my weight has risen upto 67 kgs...
and today morning - it was a shock...
it was 68.5 kgs

I do not find any reason why it shud rise like this since i m eating a very nutritious diet

yesterday's diet was
Breakfast- 2 egg whites, 1 slice whole grain slice
Lunch- veg clear soup (home made), 150 gms chicken
Dinner- Veg soup + 150 gms chicken
Post dinner - 1 big bowl of papaya

and i eat muesli, bran chapatis, oats, dalia, veg sandwich etc etc

but this sudden weight gain is unexplained

plz advise