I'm looking for a specific work that had Castiel as an Alpha skinwalker who sired Dean, who then became his mate. Dean is pregnant but afraid of Castiel's reaction. Discomfort from pregnancy forces him to stay mostly in a dog-like form. Castiel is worried about what he thinks is an illness, which is not common for skinwalkers. The pregnancy is uncovered by the end, but there is a happy ending.
Please help? Thank you in advance.

eta: found, thank you so much! link is in comments.