That sounds like a big and sudden jump. Was the sonographer confident in their measurements?
I found I had to do lots of corrections in late pregnancy - especially in the evening after my meal. Silly question, but have you increased your testing to see if there are sneaky highs coming in? I found I had to adjust my diet a little too.
I can't remember who it was, but I'm sure a lady here was told she was having a big baby and then it turned out not to be that big at all.
Don't panic {{hug}} Concentrate on monitoring your BS so you can be sure all's in target, and try to keep calm. Even if your baby has increased in size, at least your team will be prepared and will do what's best for you both.