I'm 31 week and last night I was helping DH in the kitchen. I wasn't doing much but was standing for quite a few minutes. Very suddenly I became short of breath and dizzy. I was on the verge of blacking out but as soon as I sat down I felt fine. The bump has definitely had a growth spurt in the last day or so and I am massive. Is this normal and my body's way of telling me to rest or should I be concerned?