It could be that maybe the Ob grazed you a little when he did the swab and that's what the blood is from. At this stage of pg it isn't uncommon to have a lot of mucous either and if it mixed with the bit of blood, it could make it look like you've had a show. But if you really feel that there is something going on in there, by all means take yourself to the hospital - I know it can be a hassle when you live so far away (I am 80km from my hospital) but it can really give you peace of mind too.