Roller Coaster

I am on an emotional roller coaster. There is no control of the ups and downs nor the speed at which I go from one to another. Sleep is so hard to find now.
My heart feels as though it is breaking right now and there is a very real pain that aches through my body down to the very tips of my fingers.
Questions of doubt seep into my head during times such as these. I know I am weak. I feel I have nothing left. How is it possible for a christian, with the most wonderful gift of salvation and love, find myself so destrought.
I have battled with loneliness for the vast majority of my life. I seem to never really fit in anywhere. I know that Jesus will never leave me nor forsake me and will go with me even until the end of the world...but somehow the loneliness is there. The sad part is that I try to associate with others and make friends. I feel like you need to be a friend to have a friend...apparently I am doing something really wrong.
The roller coaster I am on has been in a downward plunge for a day or so now and shows no sign of slowing or leveling off or ascending this hill any time soon.
Lord, please help me!