Confused!!!

Hi guys,

So I got my last period on the 21st of April till the 25th. It was a week late. I had been off the pill for about 2-3 weeks prior to my period coming which is why I suspect it was late. However I started a new pill at the start of that period (about 2 weeks ago). A week ago I missed about 2 or 3 pills in this new pack and since have been having what I suspect is old blood (as it is dark brown). Would this just be because of missing my pills? I have missed pills before but I usually always bleed a little and never really have the old blood or at least have it last more than a couple days. I had unprotected sex on the 3rd where my boyfriend came in me which I think was also around the time that I missed the pills. Do you guys thing that what I’m having now is just old blood and is caused by missing my pills? I feel like ever since I went off my last pill my body has been weird and so I’ve been having a hard time understanding and also figuring out when my period is due as well as ovulation. Any advice or similar stories would be very helpful!!! Thanks 😊