My friend had an ectopic pregnancy and her test was a faint positive and then went negative, even bloods at hospital were negative. Her pains were but down to ibs until one morning she was crippled with pain. She had ectopic and had to have her tubes removed, she was 8 weeks gone! Her pains were only mild to start with and then started to get back. They were surprised the baby grew that big!
I'm not saying this is happening to you just best to get checked out. X