Dizzy spells since giving birth

I am a mom of 3 and I’m not really sure but I’m trying to figure out what could be wrong. I have been to countless doctors and they seem to just say it’s vertigo. Since I had my third child I’ve been experiencing dizzy spells. This never happened before this child. At first I brushed it up to being exhausted /tired from a new baby. But then it got to be about 6 months in and they got more frequent and more lengthy. This is when I went to see drs. They ran all my blood work, everything was normal. They did an MRI 6 months ago, it came back normal. Even so though it’s getting so much worse. I seem to be okay if moving. But for example, church really kills me with the words for songs up on the projector and standing still while reading them ( I’m so unsteady and closing my eyes makes it worse) I haven’t passed out yet but am very much so in a daze all day. Please give me all issues that it could be. I am overweight and take vitamins daily. Please don’t tell me to not take medical advice from FB because I’ve been to numerous drs and they are all telling me my levels are ok and it’s vertigo. I’m on antivert medication too. I’m also mixing up words. Like I know what I want to say but it’s coming out like too fast. For example, " how was your Easter" that’s what I’ll want to say but I end up saying " how was your Easter bunny…" like my brain is thinking it but it comes out different. It’s to the point where I’m starting not to want to leave the house without someone who can be with me in case I do pass out. I want to find out what this could be then bring those up to my dr. If anyone has experienced this please help a girl out. I hate feeling like this all day everyday. Please be kind. I got 3 kids to take care of . Thank you.