Hi i had exactly the same thing, a tiny tiny amount of blood like a little streak ( only when i wiped),i too was severly constipated, i had it between 5 1/2 weeks to 7 1/2 weeks, I rang My Obs he was very reassuring and said to put my mind at ease he booked an ultrasound scan at 7 weeks and all was fantastic baby was the right size with a good strong heartbeat, the sonographer said everything to do with bubs is perfect, she found the tiniest tiniest amount of blood below the sac, which would not affect bubs she it was soooo tiny like a hairline!!!!

She said it could of happened when bubs implanted. So when i went back to Docs he said the scan was so good a 95% chance of carring bubs to full term, he basicaly said by the looks of it you're not going to miscarry!!

So to get reassurance go and see the professionals and for that extra reassurance see if you can get an ultrasound, because no matter what anyone says it will always be at the back of your mind

Good luck Hon, I know what it feels like!!!