Water retension has many causes. Yours does not happen very often. I feel you can exclude kidney, cardio or liver problems from the usual causes.
Yours is accompanied by a blood pressure spike. Any one of the following could be the responsible.
-Certain medications -antihypertensives (clonidine, calcium channel blockers, beta blockers or methyldopa), corticosteroids, progesterone, estrogen, antiinflammatories and anti-depressants.
-Anemia (you can get a CBC test done to rule it out)
-Stress (you suspect this one
-Increased aldosterone secretion in pre-menopausal women (cyclic edema)
-Food allergy, genes (it can be hereditary)
-Protein malnutrition (not enough protein intake from diet)
-Any drug that causes sodium retention
-Excess sodium ingestion
And, of course, the blood pressure spike is a direct result/consequence of the edema.
As Ms58 recommends in her post, you should have your meds reviewed and try to achieve controlled blood pressure. Try to avoid getting emotionally stressed out, eating salty meals (even one could bring on an edema & a BP spike), and greasy meals. I just read about a study done on healthy young people with no history of hypertension. Just one greasy meal resulted in an average increase in their blood pressure 1.5 times above normal. Their BP was measured both before and two hours after the meal. Consistent consumption of greasy stuff effects blood pressure.