Have one cold foot, warms when stood up but cools when sitting, could this be a deep vein thrombosis? I knew DVT cause warm limbs, can it cause cold?

Not usually. dvt will usually have swelling and warm extremity. Sometimes varicose veins or venous insufficiency can lead to discoloration of the extremity. The temperature changes are unusual but possible with venous engorgement. If persistent then you should have an evaluation. .