Had Unprotected Sex. Started Bleeding Before Period, Tingling Sensation On Stomach. Worrisome
In the setting of regular 28 day cycles, and intercourse on the last day of your period, then conception at that time was extremely unlikely. In fact, if you had conceived at that time, based on the timeframe that you are describing to me, a pregnancy test would be positive by now if you were pregnant.
So go ahead and do a test - it will probably be negative but this should be done anyway to be sure. If it is negative, then the right lower quadrant discomfort might be related to an ovarian cyst, perhaps related to ovulation. If the pregnancy test is positive, then you need to get in to be seen as soon as possible.
I hope that this helps. Please ask if you have additional questions for me.