My car is smoking and jerking slightly

I randomly checked my oil and it was low. So I went and bought some. I could not remember which weight to get, so I got 10-40 (which when I got home I found out I usually get 10-30). Well I put the oil in and then checked the stick and it was the right amount. The next day I drove it, the gas pedal would not budge when I got up to forty two mph and when it finally started working, my car started smoking from the exhaust pipe and kind of jerking and the smoke was kind of dark grey and smelled bad. I checked the oil and it was way over the limit. So now every time I drive, the gas pedal acts funny and then my car starts having greyish smoke almost white like coming out of it. This last time driving it, my engine was quieter than using and my car was not reacting to the gas pedal being pushed. I pulled over checked the oil, it was normal and then crunk it up and it drove normal. I have only been driving a week like this, since I have no other car. Could I just change the oil and it would be fine again or is it something else?