Seeking Help on My 18 Month

He is probably nauseous and does not have anything in his belly. Nothi g to freak out about. Maybe he swallowed the wrong way, got a bad taste in his mouth. Maybe he is getting sick. See what tomorrow brings

Sounds like excess mucous to me. But if you suspect at any time your child has "gotten into" something, call Poison Control immediately.
Better safe than sorry.
No O. here is going to be able to tell you 100% what this is with your child today, though.

Look around for any cabinet doors or closet doors open. He might have just gaged on his mucus. Keep an eye on him and call poison control if you suspect anything.

That sounds exactly like the type of vomit that occurs when my youngest has a bad cold. It's snot from post nasal drip draining into his stomach.

Is he teething?
Teething can sometimes create a lot of saliva. At that young age, they cannot nor do not swallow. It then accumulates in their throat etc., and they may throw up.

Or, if he is sick, then mucus accumulates as well, in their throat and being they cannot "spit" yet nor know how and being they don't know how yet to cough it out, they may throw up just from the accumulation of mucus in their throat.

Take him to the Doctor.

The vomit might be overwhelming, all these fluids. I love buggie wipes at all times, very helpful and they smell so good.

My son did that one time when he was 7 months old & I had to switch
from breastmilk (it dried up w/no hope of getting it to come back in) &
he was on formula.
My husband held him over his arm (face facing down face towards floor)
so he could puke it up then used the suction bulb they send you home
from the hospital with to suction out the slime.
We then called the advice nurse afterwards.
So I would call the advice nurse to be sure.
You an ALSO call the poison control center if you're unsure if he got into
anything!