Try not to worry Silverbell (ha ha I know). I've found this little one has been incredibly active throughout, but will then throw in a couple of quiet days - usually corresponding to when I've been running around a bit too much. At 22 weeks there is still a ton of room in there for your little man to do his backflips without really too much of an impact on you.
If you're really worried, why don't you go and get a scan just to set your mind at ease. Having had a few scares myself I really think listening to your body is the very best thing you can do, and if you have concerned get them checked out. The worst that will happen is you'll feel a bit of a goose for stressing when nothing is wrong, and I don't know about you, but I can do goose pretty well ;-)
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