Ok first off you've misspelled the medical name of the antibiotic you're using, which threw me off at first. It's CEFTAZIDIME, better known as Fortaz in the US. If you're going to be a doctor please learn to spell medications properly.

I'm going to assume that you're not in the US since you can purchase antibiotics over the counter. Here it's prescription only.

You're going to have to figure out the dosage based on the strength of the medication and you're snake's weight. Since you're in med school it should be a snap (I hope).

Fortaz should be injected in the front third of the snake, into the muscle along the side halfway between the spine and belly. To avoid damaging the scales slide the needle under the rear of the scale before injecting the snake.

Expect your snake to object rather strenuously to being injected. Even with my ball pythons it was a 2-person job, one to hold the snake, the other gave the shots.

You can also look up mouth swab treatments for mouth rot, I know they exist but not what they are offhand.