Always compare your legs to each other. Does one look bigger than the other? More Swollen? Or red? Then, how bad is your pain? Usually with a blood clot, the pain is fairly severe, and generally doesn’t go away, like you’re describing. WisconsinWildcard is definitely more an authority on this than I am, but as a nurse, albeit a psych one, I’d say if you have any redness, swelling, and/or area where it hurts is warm to the touch, coupled with pain that not only hasn’t gone away but has worsened, I concur with getting checked out ASAP.