No, you can't ignore it. Something bad is definitely happening. Forget about butterflies in your stomach; this feels like you have a tangle of snakes writhing around in your guts. When you pull up your shirt, you can actually see your skin stretching and bulging, like something was pushing against it from the inside.
Whatever that seed was, it obviously was not safe for human consumption, and you have no one to blame for this situation but yourself and your own stupidity. However, maybe it isn't too late to save yourself from whatever is happening to you. If the problem started when you swallowed the seed, you think to yourself, then maybe you can end it by bringing it back up again. With that in mind, you open your mouth and force your finger down your throat, trying to make yourself puke.
You cough and gag, but nothing comes up, so you keep trying. The squirming sensation is beginning to spread beyond your stomach, and you're becoming genuinely frightened. You want this thing out of you now! You push your finger further down your throat, choking and retching until you think you might pull a muscle, and eventually you get a result. Too bad it wasn't the result that you were hoping for.
Rather than vomiting up the damn seed and getting on with your life, your final heave brings up a white tentacle-like thing. Actually, you only bring up part of a white tentacle-like thing. The rest of it is still down inside. The part that you can see is nearly two feet long and as thick as your wrist, smooth, and still twisting and writhing around. That solves the mystery of the wriggling sensation.
Unfortunately, it's also blocking your airway.
Desperately, you grab hold of it and try to yank it the rest of the way out so that you can breathe again. Another foot and a half of the thing comes slithering out, but after that all you get is a nauseating tugging sensation in your guts every time you pull on it. The thing is firmly anchored inside of you, and the edges of your vision are going dark from lack of oxygen.
Too bad you didn't think to call for help as soon as you noticed something was really wrong with you, because now that you're being suffocated by a mutant tentacle stuck in your throat, it's isn't an option. You try to run back upstairs to get help from your parents, but you collapse before you even get to the steps. As everything fades to black, your last conscious thought is the realization that the squirming crawling feeling is still spreading through the rest of your body.