Why has my skin (mainly face) suddenly become so sensitive to sunlight i have to wear sunglasses and my skin burns and reacts even with high sunscree?

Hard to say: It is possible that some part of your skin care routine includes something that is triggering the increased sensitivity. If nothing has changed you can still develop a sensitivity to a component of the material over time. As this is interfering with your enjoyment of life I would consult a dermatologist on the problem & learn of ways you can reduce the sensitivity.