I'm sorry I can't help. I've never experienced anything like that with any of my rats. It might partially be attributed to genetics. If I recall you just got him from the pet store. He might have a poor immunity, allergies, or any number of issues that can plague store bought rodents. I'd suggest next time you get a rat that you plan on keeping as a pet to perhaps search out a rattery or someone in the area that has high quality rodents. Much like reptiles, there is a vast quality difference between what you find in a pet store and what private collectors produce. I'll ask a few people for you and see if anyone has any ideas. Hope he gets better for you Leah.

Regards,

B