What Causes Sharp Pain In The Abdomen On Lifting Weight?

I'm 8 weeks pregant and I lifted a trash bag of clothes into my car with the help of my knee to take to goodwill and I felt a sharp pain in my stomached. It's been about 3 hours and I still have the pain. Should I be worried? I have been getting craps for about a months though so I am not sure if this is normal or because of the heavy lifting.