Dean coming with him threw Spike off balance, but at least it got him out of the sun.
That was about the only good thing that happened.
After that, pain burst through him, sharp and bright from the gunshot, duller in his thigh where Dean's kick connected. Then it exploded in his head, white and blinding. He let go of Dean instantly and stumbled backwards till he hit the wall. He slid down the wall to the ground, yelling in pain, holding his head tightly as if to stop it flying apart.
It took him a while to realise his hands were smarting. He cracked an eye open and saw they were smouldering from the exposure to sunlight and immediately wrapped them round his chest under his coat to put a stop to that. When the agony in his head had subsided to a nasty throb, he squinted up at Dean, face even paler than usual, eyes wide and afraid.