Because of your history, if you can't see your doctor go to the ER. It's proably just that you need to adjust blood pressure medications, but it could be something worse. If you are still on the pill, you are still at risk of blood clots.

This is not a medical advice but I believe you have what's called edema. It is the swelling caused by fluid retention, i.e.excess fluid gets trapped within your body tissues. You mentioned that you're currently on antihypertensive medication and it's worth knowing that some drugs that belong to this class has edema has its side effects. Now that you have an idea of what's causing the swelling, you may want to discuss it properly with your Physician so he can properly manage your swelling. It's worth noting that edema is not life-threatening so continue taking your medications. Note any other side effects you are experiencing with your meds aside from the swelling. All these observations will be valuable to your doctor the next time you see him/her.

Best of luck to your health!