Well i can play a lot of songs fine with no problems, but the ther day i started to notice my little finger sometimes curls up or goes down when i playa note with my third finger.

I have tried doing lots of chromatic scales ,but they seem fine its, just on fast songs where my little finger goes dodgey. This can also sometimes happen to my middle finger althought this is generally not as bad.

Can anyone offer any tips on how to get my little finger to be straight and not tense up, and any exercises ic an practice constantly ot help me ?

Thanks in advanced
Your fingers are supposed to remaind somewhat curved most of the time. It is more natural for you hand. Unless this is interfering with your playing, don't change anything.
i mean it rearly curls up like it is rearly tense. I know they are supposed to be naturally curved but when my little finger goes dodgey it goes realy rearly curled up
This happens to most people. Im lucky; it doesnt happen in my fretting hand.

Just keep practisning
mine curls up when i play too. unless like it goes limp and starts floppin around on the strings like a dead fish, it really doesnt matter what its doing.