We will certainly keep you and your son’s journey in our prayers. He may be a bit young for this site as well, but I believe they have a kindergarten section. Khan Academy is what I am referring to! We use this as a study supplement to my son’s normal coursework and it is pretty awesome!
For sections that he has questions on that I cannot answer, the site offers a “learn the lesson” option where you can link to a YouTube video that explains the concept. You can set up a parent account and link your son’s account to it, so he can see his progress and you can as well!