That movie where a boy falls through a brick wall during lightning storm amd travels back in time

Oke so I remember vaguely. There is a boy who falls through a brick wall during a lightning/thunder storm and travels back in time. Here he meets a poor girl who is afraid of going into her own house because of bombing, so she sleeps in the dog house.

And the end was something about the boy giving an ant of the girl some asthma medicine so the ant could life longer and the girl grows up rich. He goes back to his own time and bumps into the girl who is now a old women on the graveyard bringing flowers to a grave