I am suffering from constant weakness / dizzy spells. I can't stand up or walk around for more than 30 seconds without feeling like I will faint?

DIZZY & FAINT. Many possibilities including middle ear problems, electrolyte abnormalities, glucose problems, thyroid issues, anemia, pregnancy, irregular heart rhythm, blood pressure problems. There are many other possibilities. Bottom line... a face-to-face assessment by your physician is definitely in order... sooner rather than later.