You would not be feeling those physical signs of a pregnancy that quickly after having sex. You were probably just experiencing some discharge that got backed up after your cycle ended. Try to be calm, do not stress, and see what happens with your next period. Stress and anxiety will not make it come, so make sure to relax.
It's very possible you have a UTI, in which case, drink lots of water, flush it out of your system. Cranberry juice as well as lots of vitamin C will also help to act as a "quick cure" for UTIs. UTIs are more common in women, and I get them every so often. If you have a diet that's high in liquid sugar (pop/soda, energy drinks, sweet tea, etc), you'll be more prone to UTIs.
