Okay why would I have bleeding with clots and such but my hcg is still doubling and rising? I'm so confused.

Last week I went for my first beta Wednesday and it was a 3.88. Then I went back Friday and it rose up to a 6. Saturday, Sunday, and today I've been bleeding with clots in it. And I had my beta done again today and it doubled and came back at 16. How is my hcg still rising whenever I've had all of this bleeding? I thought for sure it would be down at 0 today when I went. I was shocked. I go back again Friday to my specialist to have my beta done again. Has this happened with anyone else? I already had a miscarriage in August. Trying not to get my hopes up. I'm just confused on how this is possible. Has this sort of thing happened to anyone else?