squeezing foot pain

For the past three days I have been having severe foot pain. The pain is sharp sqeezing pain. I cannot bear any weight on it. I visited the ER on Sat morn where they did some bloodwork and said they did believe it was a bloodclot. The foot looks fine it is a bit swollen, but otherwise looks normal! It is just unbearable pain! I have not fallen of dropped anything on it, I am at a loss to understand what is going on! But As it is, I am bedfastwith it like this! Any thoughts?
***********************************
Running Shoes|Fitflops