Strange Unknown Eye Issue

Hello this is an issue that has plagued me since the start of the year. I have/had two naked rats. Lykos in February started forming a milky eye, a nasty smell from it and it was always closed. Got meds for the vets then it got well for a week then immediately came back full aggression. It ruined him he became skin and bones no muscle. visible spine and could feel the tail bones and his personality changed to confusion and aggression constantly. Went back to the vet said if these antibiotics didn't help in 10 days he'd have to be put down. He died after 5 and I was heartbroken. Now this month his brother Loki has developed the same thing at the current moment he's just got a visible spine, walks/hops funky, more brash personality and constantly shakes his head though the vet said it wasn't an ear infection. I'm prepared for him to pass from this, but I'm just wondering what on earth this is?? I cannot find any information that is similar to this and I've had the worst vets possible and there's not many exotic vets around. Does anyone have a slight clue on whay it is?? Please if anyone knows a slight idea that would be wonderful this is absolutely hurting me not knowing whats slowly destroying my heart rats