Sudden weight gain at 30 weeks

Sudden weight gain in the last week has seen me put on 1.7kg (which is approx. 3.8 pounds) in 6 days! Over the pregnancy I had gained a total of 5.8kg (12.7 pounds) but this sudden increase has me nervous...

We are in the middle of summer so experiencing very hot days in Aus and it was Christmas but I really dont think I over did it. This just seems too extreme...

I have passed the glucose tolerance test already and checked my blood pressure which is a little higher than my normal but not in the high range...

Has anyone else experienced this in there 3rd trimester?