What is in Alfredo that makes my stomach sick?

It gives me bad cramps and severe diarreah. I thought it was just the
Alfredo spaghetti sauce. After having the same results from several
different brands, I decided to no longer buy it, even though I'll miss
it, because I've gotten real tired of tomato based spaghetti sauces.
But as sick as my stomach gets, I quit buying it. A few days ago, a
local pizza place had a special on slices. I grabbed a slice of their
regular pepperoni, which I've had many times. They also had a new
Alfredo cheese with 4 other cheeses pizza. One slice of that stuff, and
I was sicker than I've gotten on the spag. sauce.

From now on, if it says "Alfredo" on the label, I avoid it.

But I am curoius what cause such extreme stomach flare-up from eating
it. Being older, my stomach dont tolerate some foods as well as when I
was young, but overall, I can eat most foods without too much trouble.
At the same time, I am lactose intolarant to a certain degree. If I was
to drink 20 oz of milk, I'd be sorry I did it, yet I can drink 4 oz and
not have any significant problems. And I tend to eat quite a bit of
cheese and cheese dont seem to bother me much at all. (referring to
block cheeses such as colby, swiss, cheddar, etc and american cheese or
that processed stuff.) I can eat cheese spread on crackers too, and not
have a problem.

Anyhow, there is something about Alfredo that seriously disagrees with
me, apparently even in small amounts. I just wish I know what it was.

What makes it different than other cheeses?