Welcome to Healing Well! I don't think it's uncommon to suddenly notice GERD--especially if it's a big flare-up. There is such a thing as "silent GERD"--you can actually have reflux without even knowing it.
I didn't know I had GERD until I was suddenly attacked after taking an antibiotic.
I have asthma, and the reflux was making it a lot worse. Actually my first bout with heartburn was when I was pregnant, but I didn't notice it again until much later.
How long ago did you start the Prilosec? It usually takes a week or so to get into your system and start working at peak effectiveness.
Generally I was given a reminder of my reflux when I took an antibiotic that my stomach couldn't handle. For me, when my stomach got going/reacting my reflux would worsen.
It's possible that you have a hiatal hernia, and it may have gotten worse recently. None of us are good at figuring out the cause of our reflux.
Are you taking the Prilosec before your meals? You should take it a half hour or so before your meals. That way it shuts off the acid before it starts. It does its best work when taken before meals.
Sometimes people take PPI's and never have reflux again. Others (like me) have a lot of breakthrough. Also most often people with a wide-open LES can't manage it well with PPI's. There are many different versions, and perhaps your doc will try a different one if you don't find Prilosec helpful.
When do you notice your reflux to be the worst? Is it during the day, or bedtime?
If you have continued problems, it is recommended that you raise the head of your bed with bed-raisers or blocks. It helps keep the reflux in your stomach.
If you don't get relief soon, be sure to check back with your doctor and see what the next move is.
I hope you feel better soon!