Why does our weight remain stall for several days, then suddenly drop?

[Comfy_Blue 285]

Every couple weeks, something weird happens with my weight loss. I'll be losing, losing, losing, then at random, my weight lose will stall and I'll fluctuate between 2 - 3 lbs. Then, it's like my body picks the lower of the fluctuating weights, remains there for several days and suddenly it'll drop and I'll find myself 2 - 3 lbs lighter than my lower weight.

For example: All last week I kept fluctuating between 175.3 - 177.8 lbs. I thought i had broken my sleeve. On Sunday night I was 175.3 and my weight stayed there until tonight, when I got on the scale and found that I weigh 173.4.

I'm super stoked, but I am trying to figure out what's going on and if it's something I can control. At first I thought it came from being less active (last week was my Spring Break, so I went to New Orleans with girlfriends. When I left home I weighed 175.6. In New Orleans, even though we did A LOT of walking, I also ate a lot of junk, so I don't think the walking helped much. I caught a cold during the trip, so when I returned home Wednesday night I pretty much slept and laid around until I felt better on Friday. When I got on the scale my weight kept fluctuating between 175.3 to 177.8 lbs)

HOWEVER, I don't think it's the lack of exercise because during a regular week (during which time I work at a HUGE, two story school and do a lot of walking, plus I stand up all day and walk around my classroom of six year olds) and every couple weeks the exact same thing happens where I fluctuate, then remain stagnant at the same weight day and night and suddenly drop a few.

What's up with that?