Kub x-ray showed no stone i am still having severe pain at night on my left side could it still be a kidney stone?

Yes: Depending on size and composition stones might not be visible by x rays, see your doctor for persistent pain.

Possible: Not all kidney stones show up on x-ray. If the pain is only at night it is not likely to be a stone. You should see your doctor for a proper work-up.

Probably not..: A kidney stone on the move will not spare you pain during day--it hurts day or night. Since you only experience pain at night, something else is causing your pain. Kub is a so so test for kidney stone, but your pain pattern does not fit. It is difficult to tell what you have based on the limited info provided. Please consult doc for re-evaluation and possible additional testing. Good luck.