What Causes High HCG Levels?

My hcg levels have gone from 98-134-141-127-367 in 2 weeks time. Thought I miscarried as I had the severe cramping and bleeding, that was when my hcg levels were at 127. In a week I was to come back to make sure levels were dropping, but instead they increased to 367 in 7 days time. What the heck is going on?!! Doctors are unsure and at this time want me to just continue getting hcg levels checked every few days. Didn t even know I was pregnant, thought I was having appendicitis, which is why I went to the doctor in the first place with severe pain. Then a week later is when I thought I was having the miscarriage contractions. Bled for 7 days before finding out I was pregnant so I had thought that was my period. Didn t bleed for 7 days, then have been bleeding for 10 days, now with only light spotting.