If you are awakening sweaty enough that your pajamas or sheets are actually soaked, you may be experiencing something called 'night sweats.'
Heavy sweating is sometimes associated with a big drop in blood pressure, and such decreases can cause a sense of nausea such as you describe.
Night sweats can be caused by infection and several other kinds of illness, some of them serious (including heart trouble).
The fact that you also experience this kind of sweating during the day with only slight exertion, along with chest tightness, may be another sign of heart problems, so as michelle says, it's time to see a doctor and find out what's going on.
I highly recommend seeing your doctor to get checked out. If you at all feel squeezing pressure in your chest you may want to not think twice about going to the er. I am not a doctor so I have no way to know if this is anything serious but it sounds like you are having issues that really need to be checked out by a doctor. Best of luck and keep us posted on how you are. Don't put this off.