Is it every time you eat anything, even drinking plain water?
I get tachycardia if I eat any of my trigger foods. I had a real bad bout a few days ago when I ate a half a cream filled doughnut. HR was 160 for a couple of hours even after taking Inderal and Atenolol and doing Valsalva maneuver.
You might try Valsalva - it's just pushing hard like going to bathroom. Look it up online. It works pretty well for stopping minor tachy vents for me.
My tach is supraventricular, not afib. It did however, send me to the hospital a few times.
115 isn't awful, unless it goes on for a long time. I get treated only when mine gets to at least 145 for a really long time or goes to 160 and I can't get it stopped.
You might try keeping a food journal (put that in the search box at the top of the page). My allergist had me do that, and we found my group of trigger foods.