Pain In Leg And Ankle, Swelling. Have Varicose Vein In Leg

Just back from holiday in Spain. I have a pain in side of my leg and now my ankle - with slight red veins at the ankle and slight swelling just beside the ankle bone. The pain is like toothache in ankle. I do have a varicose vein in that leg, but have never been bothered with pain regarding this before. I was very worried about DVT , as had been on a flight, albeit, only two and a half hour flight. Went to GP, who ruled this out, as no pain in calf muscles and no swelling or redness in calf muscles. I sleep ok at night re: this, but whenever I put weight on the leg, the pain starts again. I did have high boots on the first night on holiday and walked for an hour in them, which I am not used to, then went onto wear flip-flops, as it was quite warm. I was wondering if the pain was associated from going from wearing high-heels to flats. I would be grateful for any advice you can give me. Many thanks. Gail Hunt.