Morning Sickness Getting Better?

I'm 7w2d and saw/heard my baby's heartbeat on Tuesday at my first ultrasound. After that, though, my morning sickness has seemed to ease up. I had a missed miscarriage in April at 9w, so I'm nervous that the nausea getting better means I'm having another. Anyone else experience a relief in symptoms around this time? TMI side note: I've had bad diarrhea for 2 of these days, so maybe the sour stomach from that overshadowed my nausea?