I recently changed my brake pads but one of the screws are loose and doesnt seem to tighten.. It the top screw on the caliper... is there a way to tighten... now when i brake at times the steering wheel seems to shake...

 

Dangerous situation. I would not even drive it that way. You have a stripped bolt or bolt hole. Replace bolt or check the hole and heli-coil it or replace the knuckle.