Doesnt Understand

ok this is goin to sound wierd but i fell pregnant on the 17th of july and lost the baby on the 28th of july with heavy bleeding my hcg levels were at 38 after the lose my hcg was 35 three weeks later i went back to the doctors to check my hcg levels checked and they were 601 the doctors said i was pregnant for the second time but i had brown spotting then i went to another doctor this week and my hcg levels were at 508 but the spotting had stop this doctor also said his not sure what was goin on with my body and if i was pregnant or not i went for a scan to but no sign of pregnacies i just want to know what is going on