I had sex many times last week and was on the mini pill for this time but since i have had light brown spotting, tummy pains and sore breasts. ?

Too soon to tell: I believe your question implies that you know that the mini-pill (progestin-only) is somewhat less effective than combination hormone BC pills...perhaps 90% effective vs. 99% effective. And it is also associated with more irregular bleeding. You can't know yet if sex last week resulted in pregnancy. Wait until your period is due, and then do a home pregnancy test. Continue condoms for STI prev.