Hi Tina, I have spellings of the name as Loundes/Lounds/Lowndes/Lownds and a few others on various records. Often the registrar wrote down what he heard and spelled it as he thought correct, so we have to make allowances for these variations and it is not an indication of a change in the family name.
Unfortunately I am not on Facebook, but I will send you an email.
If you can give us the name your dad remembers for the soldier and any clue to the regiment from the photo (or even scan and post the photo here), we may be able to track him down.