hello, to start off I started with achy legs 3 weeks ago but I felt it more in my left lower leg in the behind. I went to get an ultrasound that was negative. I then started to get shortness of breath I got a chest xray that was normal and one just yesterday when I started to develop pain in my ribs when trying to breathe. I had a d dimer test which came out negative it was 0-250 but my leg still hurts and I have trouble breathing even pain,. should I go back to the ER??