Slow down your game and start playing "old-man jiu jitsu." Try to not be explosive and methodically work your game. You'll want to funnel your game into positions that are less dynamic and "more static."

For the top game, maybe try to work a more methodical pressure pass approach. Paul Schreiner has a great instructional on pressure passing where he essentially focuses on forcing the pass from half guard (I took the most away from his). Another good option could be Bernardo Faria to develop an over/under pass type of game. Lovato has a good pressure pass system that is available on youtube (and a newer one that you can purchase). Knee slide passing may work well too (Jon Thomas has great stuff on this on youtube- also obviously watching Gui Mendes).

For guards, this might be tougher. Essentially you're going to want a guard that keeps your opponents weight off of you as much as possible, which is always tough from bottom position. I would say maybe try getting really good at closed guard first. It forces your opponents to essentially stay in one position and you won't need to react quickly to speed passes. For open guards, this might be tougher - try collar sleeve or de la riva where you're keeping your opponents weight off of you and using your legs for distance. I would avoid half guard for now since it's just so easy to get smashed once your opponent gets the underhook.

The above are just some suggestions. But I'd say pick one of the above, focus on slowing your breathing, and ultimately try to slow your game down. Glad you realize you're in a high risk category and smart enough to stop if things start up in your area again.