data usage on iPhone 4

I've read all the previous threads and have not found an answer.  Since it's saturday and I can't speak with anyone for a few more hours I thought I'd at least vent.  

Just so we are clear - I have no push notifications, I fetch my mail manually and only at home where I use wifi.

Yesterday was the first day of my billing cycle.  The entire ttime the phone was in the house (with wifi) except for a two hour span when I took the kids fishing.  I used my phone twice during that time to send one picture each time to my husband.  Thats it.  

So this morning at 6AM I get a text stating the I have used 90% of my data.  In 1 day???  I have been on the 200 plan since getting an Iphone and have consistantly used about 125 except for one month when I used the phone for a GPS when we were lost in the hills of Arkansas - so that's understandable.

I checked my other 3 iphones and the data usage is:  Keep in mind this is only the 2nd day of my billing cycle and its only 7AM.  So in just over 24 hours we have all gone over what normally takes us a full month.

My son's phone that has never gone over 100 is already at 117.41 

My husband's phone which rarely reaches 50 is already at 45.68

My other son's phone which was taken away and has been turned off for the last 5 days is at 18.7

I did change my rate plan down to the 700 family talk plan staring this month - but that shouldn't have done anything to the data.

I'm really quite frustrated.  we all have IOS 5.1.1