Some bacterial infections will overwhelm even a very healthy immune system, and reproductive infections in poultry is one of these. If you catch it early and knock it down with a good broad spectrum antibiotic, there's a chance your pullet can go on to lay normally and have a normal life span.
Call around to you Tractor Supply stores and pet stores and ask for amoxicillin. It is often marketed for aquarium fish, and comes in 250mg and 500mg capsules. The dosage for a chicken is 250mg per day for ten days.
TSC often sells amoxycillin 500mg. If that's what you get, you will need to break the capsule open and divide it into two equal doses. I use a small bite of bread dipped in olive oil to sop up the amoxy powder. It's very bitter, and to get the pullet to take the bread with the med repeatedly, sprinkle some sugar on it to counter the bitter taste.