Help please

Hi y’all so I get my period monthly, so The last time I had sex was on feb 6 and my partner finished in me. Around 16th feb I got brown discharge and I had a light period (I think it was) for about 4 days. I never get my period early , I normally get it around the 27th towards the end of the month. Now that my “light period “ is over , I have been having back pain lately n cramping in my stomach. I’ve taken a pregnancy test and was negative. Should I take another one just in case ?