My 2nd toe, my big toe constantly rubs, & now i have what looks like a small blister, with a black dot in the centre its soft, & painfull, is it a corn?

Could be: Your skin will protect itself where there is increased pressure by forming a corn/callus however sometimes things can get embedded within that forming. Thia can be dirt, can be a.Scab from friction or a wart (virus). Have the podiatrist check it and offer you relief and treatment options.

Dried blood: The black dot is probably dried blood. See a podiatrist for treatment and suggestions to stop the toes from rubbing.