Pro-biotics may help
Antibiotics kill the good intestinal "flora" along with the bad.
By introducing "good bacteria to its digestive tract, it may help "normalize" things. That is what I would do personally. imho.
I'm not going to advise you not to go to the vet. Thats your call...do what you think you should.

I may be off base here, and don't know it, but probitics should help, and they certainly will not hurt your patient.
Dip a mouse butt into the powder and feed as usual.
Also, can be added to water too, initially, to help assure that the
"innoculation" of good bacteria to the Corns intestinal tract, will very rapidly establish itself.
Transfer powder into say a small pill bottle in smallish amounts to use as a dipping container, as to not cross contaminate with mouse butt bacteria , ones main "stash" of probiotic powder.
Keep it clean, kids. ;~)
There are some alarmists that may tell you to leave now and run the red lights to get to the vets, I would stop for the lights at least, at this point.
Two quality popular reptile specific pro-bacteria products I'm familar with are NutriBAC DF and Bene Bac.
"Hope it all works out in the wash" for your Corn.
I also believe in vitamin/amino acid, calcium D3 supplementation for Corn Snakes, but thats another post.
imho.