Miscarriage or period???

So I had been on the pill and then come of about 7 days ago and never got my period which your supposed to after you come of the pill ( I know not straight away) but today I “came on my period” but it’s nothing like I’ve ever felt before I’m in so much pain and have gone through a lot of pads and a lot of bloody cloths but I just want to check with soem of you because I’m really not sure what this is.

It is way bigger than a 2pence and 50pence coin and really hurt when it came out, I’m just abit worried.