During last few months when i wake up, my bite is aligned ok, but throughout day it becomes misaligned with certain teeth touching more when biting.

Swelling in disc: Traumatic occlusion or para functional habits could be leading to inflammation of the disc that your jaw rests on .....As the inflammation causes swelling the teeth don't seem to fit together right. Usually 600 to 800 mg ibuprophen three times a day for one month will resolve but what habit is causing this problem ? Injury or repetitive activity. Soft diet would be helpful too.

Might be: Might be the other way around, that your daytime bite is your "norm" and at night you accommodate. You need to see a bite expert, an orthodontic specialist, for evaluation.