I had intercourse two days before my period, on the day of my period, I got brown discharge

I had sex two days before my period. Sex on Dec23, period on the 25th.  On the day of my period, I got brown discharge and I have no idea if this is what you call "spotting". It continued until the next day and I got a small red, jelly-like discharge. It stopped and continued on the third (and last day) where it was red but very, very light. The night after sex, I experienced a weird rumbling in my stomach. I had a slight IBS kind of situation for the entire three-day period. The rumbling continues until now (worsens usually at night) 10 days after intercourse. Could I be pregnant? Im having other symptoms except breast tenderness and vomiting.