Brown spotting and cramps

[rikkyc]

Hi all
I had a positive pregnancy test last week. I wasnt trying, nor have any idea of dates as my periods are so irregular. The past 48hours Ive had light cramping and some brown-ish blood. Definitely not enough to think its a miscarriage but I had a lot of pain around top of my thigh as well yesterday so wondering if its signs of one.
Ive had scans before as previous births (2) and miscarriages have caused pain for me, and NHS investigated, I have scarring and also had a blighted ovum a year ago. Could this blood be old tissue or potentially a miscarriage? Any experience of this before.
I also have an upset tummy but not sure if that's separate or related.
Thanks Edited

Thanks everyone for your comments. Helpful to know about other situations.
I'm still having cramps and brown spotting sometimes red spotting, I have for about 9-10 days now. Very confused if this will or wont be a pregnancy. Scan booked but not for 4 weeks yet.