Were you sick after the trip in a way that suggests you picked up something while there?
Before I learned about adrenal cortex support and mild adrenal insufficiency (adrenal fatigue) I used to catch a cold after a stressful event. A good example is a concert for the band that I was in. Besides the nerves of doing the gig, there was a lot of gear to move, etc.
So I would not be surprised if adrenal fatigue after your mother's passing was related to the health struggles.