A little freaked out...SOS

So I started my period about 3 days ago, since I've been on nexplanon my periods have been a little sporadic which is normal. But this week I've had worse back pain and cramps that I've ever had, and my flow has been a bit heavier than normal... when I took out my tampon today there was this long blob kind of stuck to it. I thought it was just like a clot or lining or whatever, but looking closer at it, it seemed off...Now of course I've gone through Google and this is either just a weird period or I've had an early miscarriage... I know I'm okay, but I'm a little freaked out just cause I don't know what it is. If anyone has had a similar experience and could tell me what this is that would be great.