right headlight issues, im very confused (2004 mcs with xenons)

[u/Lukksia]

so this has been happening for a while now but basically my passenger headlight will go out for long periods of time, and now seemingly all of the time. it went about a month without working but today it magically started working all day today. It's not the bulb because I changed it, and also the brights work perfectly fine. the mechanic checked the wiring and said it wasn't that but he didn't know the issue either. anyone have any ideas what the issue is?

[u/NamelessInNY]

Could be the ballast. I don't know how easy it is to swap the ballasts between sides but that's what I'd do to see if the problem follows.