Solutions to solve the issue
1)he can go to the hospital before shabbos and just wait in case he panics and needs the hospital c”v this is the best way he can avoid the entire chillul shabbos issue
2)pekuach nefesh is docheh shabbos and chillul shabbos is allowed if his life health is in danger even if it happens all the time c”v
May he have installed in him serious faith and trust in Hashem and then he will never have any more panic attacks and may Hashem only grant him health forever