Textures glitching when going in the nether

Logging in the normal world and all the textures work just fine, but after going through the portal or logging in inside the nether every block turns black, lava, portal frame and fire glitch (they either flicker or turn gray) and the only normal textures are chests and signs; going back to the overworld through the portal doesn't fix the glitch, transparent blocks and random chunks become invisible.