Help! Blood on dipes...

My 14mth old DS wears cloth full time. Our stash is mostly bG OS and prefolds, and we have a few fleece bG that we use strictly for o/n, and fleece liners during the day.

This morning I changed his dipe and there was a spot of blood where the tip of his penis was touching the dipe. He is circed (which I regret now that I know better) and he grabs at his penis/or dipe quite often. He doesn't cry but I wonder if he is uncomfortable. I always wash with Dawn - a cold wash cycle with baking soda (vinegar in the rinse) then warm (and sometimes hot) with Dawn, then an extra warm or cold rinse. All the inserts are dried on hot in the dryer and the covers get thrown in on low for 20 minutes at the end.

This happened a while back and he got really irritated, and when we started to use fleece liners, it cleared up. What do you think is causing this? I think if he had a UTI or something, he'd cry when he urinates and be in a lot of pain. Right now I am washing the dipes with bleach in case it is a bacteria thing, but could it just be from friction? I really don't want to take him to a doc and have them give him abx or tell me the cloth is causing it... I guess I'm just looking for encouragement and suggestions, and advice from any of you who have been in this situation before...