Could it be a possible blood clot if severe, painful swelling in BOTH legs and ankles? Or would a blood clot only cause swelling of the affected limb?

Blood clot maybe? Can it be a blot clot? The answer is almost always yes. The reason? Because we don't want to miss that in a diagnosis. A blood clot affects one limb but there is nonrulenthatbsays you can not have 2 or a clot (obstruction) in a vessel that feeds or drains both limbs. The simple answer is "yes it could be a blood clot" the only way to know is physical examination and diagnostic imaging.

Related Questions

Can a blood clot cause painful swelling to occur in BOTH legs/ankles?

It's possible. Usually clots are more likely to appear in one leg or the other, appearing in both legs simultaneously is less common. However, it is possible to have clots in 2 legs at once. You should contact your primary care doctor or go to your local emergency room for an ultrasound to rule out a deep vein thrombosis or "blood clot" which can be life threatening.
Both legs swelling. It would be unusual for a clot in one leg to cause both legs to swell unless the clot is located in the inferior vena cava which drains the blood from BOTH legs. Often times bilateral leg swelling is due to other issues such as heart, kidney, lung or liver. Even medications can contribute to bilateral leg swelling. See your PMD for an evaluation.

Can anxiety cause leg pain in both legs that mimics a blood clot (w/i the redness or swelling)...2 negative d dimers and happening for over a month?

Improbable. The description of your symptoms does not sound to me like something that would be commonly found to be due to anxiety. First of all the duration of the symptoms is way too long. I would continue to pursue other avenues. If necessary get a second opinion at the university teaching hospital. Checking for spinal pathology would be reasonable and you also don't mention having had an ultrasound of your legs either. It would be premature to conclude that this is due to anxiety. Bestwishes.

23 pain cold in both legs dull, happens often no visible swelling spider veins since young. Not likely a blood clot in leg right if both legs ache?

Not likely a clot. Emily, if your legs have been having this dull pain for years, and it's on both sides, it's very unlikely to be a blood clot. However, the fact that they hurt and feel cold should lead you to have a family doctor check you in person at some point in the near future.