Whilst I go through my overworld Nether Portal, I set on fire

(Ever since I made an extra portal in the Nether to link to my end portal in the overworld)

whener I go through my main overworld portal now when it  teleports me( so I have no coordinates) at that point I set on fire. This killed my friend as he had no armour on. The portal is not on lava it is on a solid platform. Likewise with all of my portals.