This happened last night or the other day. Due to memory loss I can't even remember!

I was standing talking to my son. Suddenly my legs collapsed, became extremely dizzy/vertigo-light headed and unable to get up. Took a minute or two to get myself together and legs to become stable. When I was able to stand up again I was very, very wabbly with severe vertigo.

Sadly, it happened again today. This time I was on the floor longer.

What on earth is going on?