LOL. I love how the guy just jump on the cheater wagon right off.
Dude, depending on the lenght of her cycle, she's in or near prime fertility time. So there's a chance you could be makin babies with your amorous activities. That being said, I've heard of women who display symptoms very eary but 2 days is definitely way early. She hasn't even missed a cycle yet.
A stick test should provide peace of mind. Wait at least another week or until she misses her reguarlly scheduled monthly before considering it unless her symtoms worsen or don't go away then see a Dr instead. Till then it might be best for her to assume the position and you two to resume 'being reacquainted'.
If she is pregnant an ultrasound later will determine the likely age of the fetus, and that should clear up any timing realted discrepancies.
All the best t-man. Keep us posted, you know the pack loves the drama. LOL