HCG levels

Mirna • Thru thick and thin. Stronger than ever!! TTC #3. 38 years old.
Hi everyone looking for some opinions!! Two weeks ago on Monday found out I was pregnant. I had been TTC for two years so this was a huge surprise. Thursday 05/21/2015 I started bleeding and back pain. A lot. It wouldn't go away. So being that I had miscarriage before I went straight to emergency the couldn't see anything and my HCG levels were at 189. So they told me it was to early to get some rest. And go back in 72 hours to test my HCG levels. They double.  Then Saturday same thing the bleeding got worse. So I went back to ER and again could not see nothing and since levels were low they were thinking threaten miscarriage. As was I. My levels were tested again levels went up by 50. I had made an appointment to see an OBGYN. And more blood work. HCG levels dropped. Doc told me it was a miscarriage. But to come back again for more blood work. Thursday my levels rose. So now I am confused. Anybody go thru this before?
This is my time line
05/21/2015 HCG-189
05/23/2015 HCG-359
05/24/2015 HCG-403
05/26/2015 HCG -325 (drop)
05/28/2015 HCG- 862