Ok so i found shadowmere at the first db sancuary i mount him and fast travel to the second sanctuary and when i got there my screen changed blue like when astrid kidnaps you and i start floating then i fall can anyone explain this?

Too much Skooma?

Sheogorath.

The only time that my screen changed color was when I had Sanguinare Vampiris. I didn't know that the disease did that to you; nor did I know that I even had the illness. Nevertheless, I soon discovered my ailment and ceased yanking my HDMI cable.