I'm nervous...

I'm 8w1d, and since this morning I've been having lower back pain, and now cramps. I've had this every so often, but I also noticed I'm not feeling as nauseous today as I normally do. I've had debilitating nausea for about 2 weeks now, and today I feel kinda fine. This combined with the pain and the cramps is making me nervous. I had 2 losses before this back to back, and losing this one would be really devastating. I wouldn't have thought much of it until the lack of nausea today. Would this just suddenly go away for a day? I had an ultrasound last Friday and everything looked good, the little heart was beating and growth was as expected, so I was feeling so confident.