I had mine for 4 months. I made the mistake of not having one put in before treatment started. I thought I could "tough it out". Huge error on my part. After two weeks I was begging for one. I had mine removed 3 months, to the day, after the end of radiation. At that time I was only able to drink a small amount of liquid each day. I had to force 2000 calories of Ensure down my throat each day.
As an earlier posted said, force your self to drink a little water each day. I did and retained most my ability to swallow. Of course I was on enough pain meds to drop a horse :)
Oh, and don't laugh or cough when you've got the end of the tube open. On a couple of occasions I shot stomach contents out of my tube, about 20 feet. It was a mess to clean up, but funny as hell looking back on things. There's a small stain on the wall. When I see it, I smile. Don't ask why, but I think it's because at the time I was sure I'd never feel normal again.
Keep your chin up. You'll get through this.
Tom