I am happy to help you.
When you were bitten did it break the skin and bleed?
Is you hand swollen or bruised?
Are you diabetic?
Does you hand look blue or feel colder then the other one?
If you didn't already you might need an xray just to make sure you do not have a hairline crack in one of the little bones in your hand.
It is also possible that when you were bitten it damaged a nerve.
You could also have a little blood clot in there obstructing blood flow or some slight swelling.
Go to your doctor and let him get an xray to see if there is a fracture and then he can go from there on the treatment if any is needed.
You might just need an anti-inflammatory.
Do have it looked at.
Best wishes to you Margie,
Some possible causes is that maybe if you do have a fracture it worsened as you used it.
You could also have inflammation in there that is getting worse.
Carpal tunnel is also a possibility.
You can read about a lot of possible causes here:
Hope this helps.