6 weeks pregnant and bleeding

Lindsey
It is so stressful I have been bleeding for 4 days now.. Doc says everything looks good, HCG levels have been doubling and aren't going down... But I don't understand why I'm bleeding! I have slight cramps and bleeding is like normal period... Wish I knew why.. Doc said if it's a miscarriage cramps would be severe and I would be changing my pad every hour. Anyone else had this issue?