I think I'm going through a miscarriage without knowing I was pregnant for sure.... :( my period was…

I think I'm going through a miscarriage without knowing I was pregnant for sure.... :( my period was late but I started spotting the past 2 days. Then today I'm bleeding excessively with a lot of back pain and a throbbing cramp pain. I have a lot of blood clots and this quarter size clear sac came out with a liquid inside. I feel like I'm going to throw up any minute. Can someone please let me know how it feels and what happens? I've never gone through this.