Hcg blood tests - higher than expected + negative urine test

stacey
Hey ladies any advice or anyone had similar problems. I have been trying to conceive for about 6 months now. I wasn't feeling 100% over the weekend so on Monday took a test - very faint but was positive. Prior to this I had brown discharge for 3 days. I went to my gp as the week before I had cramp like my period was coming along with the brown discharge which I hadn't had before. Bloods were taken tueaday and I was asked today to repeat them as my hcg level was at 4 (Dr said anyone 0-2 is non pregnant and someone who is 5+ is pregnant). Re done pregnancy tests and they are both negative? Period was 2 days late - was heavier than normal for 2 days now has went to coming and going. I am awaiting results on Tuesday but if I am not pregnant (which I think is sadly the case) then why was my hcg levels so high?