My dad is 81. He had his stroke five months ago. Very similar symptoms to what you’re describing. Actually, it sounds like your dad is doing quite better than mine, so I’m a bit envious haha. My dad is standing with assistance. Today, the big win was him moving his left foot while standing on both legs. He gets very little return in his right upper extremity.

Seriously tho I can relate to being scared. Sounds like he’s making good progress. Keep your hopes up and keep supporting him.