Welcome to the forum.
It is due to some inflammation in the wrist which is swollen.
for diagnosis whether it is sft tissue injury
yu shuld get a x-ray done
Therefore, I would suggest that you take a good anti-inflammatory drug. You must also apply hot fomentation along with local analgesic
spray in the area of the swelling. If the pain does not subside, then you can also take a painkiller to reduce the symptoms.
If the condition does not improve then I must ask you to visit your physician for an examination.
I hope this information has been both informative and helpful for you.
You can consult me again directly through my profile http://www.healthcaremagic.com/doctors/dr-saurabh-gupta/64132
Dr Saurabh Gupta.