Hi there. Perhaps he is experiencing a “reflux flare” which I’ve seen referred to in other posts on the site.
My son is 15 weeks and the same exact thing has been happening to him.
It’s very messy, depressing, and frustrating to say the least.
I don’t really have much useful advice (if I did my own son would not be spitting up so much as well) except to say that I am sorry that you are going through this.
I hope things get better for you and your little one,
verykeri