Why do i only get tendonitis in the morning ?

Probably tendonosis: Usually what you are describing is tendonosis, not tendonitis. This is not necessarily acute inflammation, but chronically damaged, scarred tendons. With rest, the scarred tendons lose their flexibility and become tender. With mobility and stretching, this gradually improves.

Water: Fluid shifts in our bodies all day, extra-cellular fluid, fills your foot after a busy day, floods back into your face and hands when you sleep. Thus certain areas of the body may be more inflamed or swollen in the am and others feel better. When asleep we often assume positions that awake we may not seek form flexed wrists to curl up up knees thus many areas may ache in the am.