15+6 small amount of bleeding today..

So when I went to the restroom a little while ago I noticed some dark red blood when I wiped. It wasn't a ton but it was enough to take several wipes before I didn't see anymore. I immediately got out my Doppler and heartbeat was good in the 140s. My doctor said that as long as the heartbeat is there and there's no pain then I should just take it easy. I was doing a lot more today than I have been. Now I'm lying here analyzing every twitch in my abdomen :/ I haven't had any bleeding since I lost one twin at 5 weeks. No sex since Friday. I keep checking the heartbeat to make sure it's still there. I know occasional bleeding can be normal, but it's hard to be rational when I'm so worried. Last baby miscarried at 9 weeks and I just want this baby to be ok!