Unprotected sex, and emergency contraception used but very strange period

Ok so basically I had a period on the 26th September, which was normal and lasted for 5 days, as they usually do (and may I point out that my periods are like clock work, never late, never early, always bang on time!). I then went away with my b/f for my bithday on the weekend of the 9th October, which according to my cycle is the weekend I should have been ovulating. We are not ttc at all, however we did have unprotected sex on the saturday (10th Oct) evening/ early hours of sunday (11th Oct) morning, and also when we got back. We arrived back on sunday evening and I went and got the morning after pill on the tuesday 13th Oct, where the nurse told me that as I hadn't taken it immediately the chances of it working were decreased. So my next period was due the 24th Oct, however it arrived early, and it was not a normal period at all. (WARNING TMI) It was thick, dark brown in colour and mucus/stringy in texture. It also wasn't a constant flow, it was there one day and gone the next and there again, and it has now reduced to just a faint pink smear when I wipe. I have taken one clearblue hpt which was negative, however I'm not sure whether to believe it or not. I have another one which I will take in a few days time, but please any advice offered would be extremely appreciated as I am very confused.





p.s I have had what could be considered as 'symptoms', such as extremely painful lower back, sore breasts and abdominal pain, all of which (apart from the back pain) seem to have calmed down for now. Oh and I think I am urinating a little more, but that could just be my mind playing tricks on me!