Yes I had a terrible time after my ds was born. My right wrist was very like you describe.
It wasn't straight forward though, several different things were going on and I think I'm me, they all conspired together, so it might take a bit of unpicking and eliminating.
I have hypothyroidism and by 6 months was unwell and wasn't in the right dose. Later I was on too much and had similarly bad joints actually. So that could be checked.
My ferritin was 50, only borderline, however it's been that low again recently and since I've started getting it up my joints have improved again.
Vitamin d was checked and was a tad low. It's common to be low at this time of year and causes lots of joint issues.
I was later diagnosed with hypermobility syndrome. If you had spd, there's a possibility you have some hypermobile joints. I became much looser post baby. Over worked joints start stiffening up. However, in me, the additional issues of ferritin and not being on the right thyroxine level for a while etc means I can get weak quickly (as low thyroxine weakens muscles, too much does too). Now all that is sorted out I'm much better.
More recently I discovered I had asthma (!!) following a bad chest infection but I noticed I became weak then too after a long period of not breathing 100% well (it's mild). I think lack of sleep also contributed to weak muscles too - hard if you have a little one. I coslept to get more sleep.
But in me its been a combo of all of it and getting it all sorted out. I've been having some bad nights again recently and coping fine.
So - see the GP, get things ruled out. See a really good physio (I found a sports physio good) to see if they can help including some strapping up and support belts etc for short term use. Try to pace yourself as much as possible.
Magnesium and calcium can help with the stiffness too. 