It will die if you leave it alone for a few days. Old-Timers like Ojitchi, Oyajitchi and Otokitchi die at a certain point, but it's either you didn't care for it correctly, or it's time for it to die. Usually, if you take care of an oldie Tamagotchi, it might be able to live for a few short years. On a V4, for example, if your Tamagotchi isn't married, "it will grow old until it passes away". Scientifically speaking about your Tamagotchi, your Tamagotchi has morphed into an oldie, and it will die in a few short days.