Just plain down & I can't seem to shake it.....

Feeling really down, frustrated, just plain sad......
Went to run Saturday in Vancouver the pain in my thigh was too much to bear & I could not run the 5 miles.
I could barely walk on Sunday...took lots of Advil to try & manage.
It is Tuesday & I'm not feeling any better, in fact I barely got any sleep last night because of the constant ache in my thigh.
Running is hard enough why is it being made so much harder for me with whatever is going on with my leg??? First my calves (which seem like nothing now, I'm wondering what I was thinking about complaining about them) now my leg.
I just want to get through this & still be running & not start from square one!!!!