It is all quantum mechanic, i.e the Heisneberg uncertainty principle (HUP) is within the framework of quantum mechanics, not of classical particles running along on straight tracks.
What does it mean for a single photon? It means if one measures the $x$ coordinate very accurately, the $p$ component uncertainty is constrained by the HUP.
The HUP says nothing about scattering, and the changing paths that you draw.
In the above bubble chamber picture we see one photon ( a gamma) hitting an electron and coming out with a number of charged tracks. In bubble chambers the accuracy of measurements is microns, and the HUP is fulfilled automatically, as the accuracy of momentum measurement is in mev/c. The uncertainty in momentum will be within the measurement errors that will give the momentum of this gamma.
When a photon interacts, which it has to do if measured, it is then that one can check the HUP.
Maybe you are confused by the virtual loops that can exist within the HUP envelope, of particle/antiparticle, in vacuum . These because the particles are virtual the particle momenta are not on mass shell, and they continuously change under the integral that the loop represents. For momentum to change one needs a real interaction vertex, as the gamma electron scattering in the picture above.