Hi was wondering if anyone could maybe give me some idea on my daughta's rats rapid weight loss?

This past week we have noticed her male baldy rat has lost quite abit of weight, we have noticed he is losing a tiny bit each day he's backbone and ribs are really showing now, i know u can see baldy rats backbone anyways but his backbone is really badly showing now.

ive felt for lumps etc coz i thort maybe a tumer could be the corse but i cant feel nothink?

He has been eating and drinking normal and seems active enuff but his weight has just dropped of him

has anyone got any idea why??? he looks like skeletor lol.

we are gonna ring vets up monday but its still just the wondering thats getting me.