Nether portal spawn

Whenever i get into my nether portal, i spawn hundreds, sometimes thousands of blocks away from the actual portal. For example, i once went ito the nether, and instead of spawning at the portal pike usual, i spawned in a ramdom place, i died. Another time, as i was getting out, i spawned in a ramdom place. By the coordinates, i found out i spawned about a thousand blocks away. After walking for hours, i got home. I have not gotten in the nether portal ever since. Please fix this, it happened to my fried too. With this glitch, i have not been able able to finish the game. Please and thankyou