Long so I don't miss anything..
Picked up our new rat's from "support adoption for pets" in P@H (I know, I know)
Two lovely squishy 5 month old males 
one with a severe head tilt 
Noticed some Porphyrin staining when we picked them up on Thursday, thought nothing of it as after 10 rats I know they can have an excess whilst stressed. 'Tilty' has been standing at the top of his cage asking to come out almost constantly since we picked him up, loves being stroked and cuddled, even got him to brux and eye boggle while rubbing his side completely in love with him and the other rat is slowly warming to me and falls asleep being stroked, not at picking up stage yet though.
Yesterday I went to open the cage and take 'tilty' out for his hours cuddles and run around as usual and it was as if someone had swapped him for another rat. He was more than happy to be picked up out of his cage but as we sat down he jumped off me and ran in to his carrier. He looked terrified of something so I stroked him and spoke to him, all fine. Went to pick him up and he started screeching I took him to his cage and put him back with his friend, as soon as he was in he immediately ran to the bars to come out again. I opened the top and stroked him,fed him some treats thinking he must be having an off day and left him to it.
Went back today to see if he was any better and the ratty's hammock has lots of streaks of porphyrin, none on the white rat but a tiny bit round 'tilty's' nose.
He's also clicking occasionally as he walks. White rat seems fine and happy. Both eating lots of food and drinking water.
Could this just be normal settling in stress? Poor boy's been jumping round his cage and seems almost manic. I tried taking him out today and he screeched as I picked him up again after end of free play (Which he spent trying to hide)
Will obviously take him to the vets tomorrow if I need to.
Feeling tearful as it is after my cat being pts on Friday, I don't think I could handle anything serious being wrong with him.