9 weeks preg. red spotting. or usually tan discharge. called nurse says normal unless more spotting. should i be worried. had ultra 7w3d had heartbeat?

Reassuring that...: Reassuring that you heard the heartbeat at 7.5 weeks. Still possible to have a miscarriage, and there is not way to tell you with certainty that the new red spotting isn't this, but if it is, there is nothing to do to prevent it. So i would suggest taking that as the positive sign it is, relaxing, and looking forward to your next appointment, at ~11 weeks, when you should be able to hear it again!