Why Every Time I Stand Up I Get Very Dizzy And Everything Goes Black For A Few Seconds?

Question : For the past few months, every time I stand up I get very dizzy and everything goes black for a few seconds. This morning when I woke up I was so dizzy I couldn’t even sit up. My feet are always freezing even if I’m hot. I wear socks to keep them warm but nothing helps. I also will get a sharp pain in my chest and under my left breast every once in a while that lasts between 5-10 seconds. Just wondering if I should see a physician or if this is normal. I’m a 23 year old female with asthma and hypoglycemia but haven’t had any issues with either in years. I keep my blood sugar stable and haven’t had to use my inhaler in years although I do become very winded from minor exercise like climbing stairs. I have a 5 month old so I’m very active/keep my blood circulating. I don’t smoke, drink, or use drugs.