What is coming out of my mouth!??!? (Pics)

I really need some help/advice!

While I was homeschooling my son I felt something in my teeth/mouth. I spit out what I thought was possibly food? idk, I looked at it and to me it looked like a seed or dead bug??? It had a slimy protective like shell around it.... It just kept coming out of my mouth!

When I brushed my teeth it would get stuck in the bristles...

It stopped but I saved one to maybe show a doctor or dentist.

I feel so itchy and scared.... I have to wait until 3pm for my friends son to come home from school. It's 1pm now so if I see a specialist it would be after he gets here or tomorrow...

Anyone know what this is??