I Have Had A Painful Leg Four 4 Days And

I have had a painful leg four 4 days and have difficulty walking. I thought I had pulled a muscle as I had a pain at the back and top of my leg but this evening the whole top part of my leg is painful. I had a thrombosis two years ago so am a bit concerned but that started with a swelling, redness and heat - this is not like that.
Thanks
Sue