About three weeks ago, I took a three day course

Patient: About three weeks ago, I took a three day course of antibiotics to fix a water infection that I had. as I am currently on the pill (and have been for almost a year now) taking the antibotics caused me to have a period. my period was regular/the normal amount of blood I would expect. through the course of antibiotics and since then I have been taking my pill within the three hour window that I usually do every day and never missed one. this week would have been the week that I normally get my period however I never got it properly – I am just experiencing spotting with dark brownish blood. I should also mention that I have been sexually active since april this year. me and my boyfriend always use condoms and the pill however around a week ago, me and my boyfriend had sex without a condom but I was on my pill. the intercourse lasted less than/about a minute as I told him to stop (he did not ejaculate at all during intercourse) and I had been taking my pills normally since I stopped my course of antibiotics and hadn’t missed one. I also understand from what my doctor had told me that I should wait at least 7 days after finishing my antibiotics course until having sex again to ensure my pills are workingproperly. the sex without a condom happened many more than 7 days after finishing my course of antibiotics so they should have been working fine. my question is, am I spotting because of the antibiotics that I took that caused me to have a regular period a few weeks ago or am I spotting because I am possibly pregnant? I have not been experiencing any pregnancy symptoms at all.