I was crouching then, I died???!!!

I was mining and as usual, I crouch just incase. I was looking for iron and diamonds for tools. Then, somehow, I fell in lava. I didnt know how that happend, but I was sure that I was crouching. I checked the place where I mined, then lava was UNDER me not infront. I didnt think much of it, so I kept mining. Then, the whole thing happend again! Now I've list so much blocks, torches, raw iron, and so much more 😭