Tmi but no pic no negative comments please

I'm cycle day 5 and I thought I had finished this AM but when I went to the toilet this afternoon and wiped myself I had this long blood clot on the toilet paper. I've being ttc for 18+ months and no luck. I have hypothyroidism and obese but losing weight and have irregular cycles but have being regular since November last year. I'm just wondering what this clot could be and should I be concerned?