Swollen fingers when exercising and feeling hot?

[speedwing]

I am in Singapore and I walk approximately 10 Km each morning. I perspire a lot during my walk and am usually very hot. My fingers swell up after or during my walk. Temperature usually around 28 deg C. My ring which normally comes off easily feels tight and cannot be removed,. After a cool shower and a little rest the swellings in my fingers subsides. Can anyone tell me why this is so???