Sudden pain in top of foot midfoot talus

Sir from yesterday afternoon suddenly I started to getting pain on my top left foot which progressively increased and even I can't able to support with my left foot to walk can't able to stand with that leg. I'm getting severe pain on top of left foot in midfoot or talus side if I bend my toes up and down I'm getting pain in midfoot. In my Knowledge I haven't injured my foot. But I use to sit for long period and even stand. Also sometimes I'm getting little bit pain in big toe but not sure but not pain in heel I don't know when I got sprain or what happend but still now I can't able to walk without support. Also if I stand only with my left foot I'm getting pain. What will the cause ? Please help