Termite damage around door

Twenty-five years after termites were treated, I am finally getting around to fixing the damage. They mostly just ate the sheetrock paper - all those termite tube remnants you see just below the ceiling in the 1st pic are on the surface, not in the wood, but all the paper on the back side of the sheetrock was gone. An exception is the right end of the 2x4 below the 11x4 header. The 2nd and 3rd pics show the worst spot where I dug a little into the board.

There are small gaps above and...

Termite damage around door