Hairloss from surgery or from using henna on my hair?

Hello! I was experiencing some hair fall recently, for approximately about a month, that thankfully has started to subside. But I would love some thoughts on this. Back in September I had a bad case of appendicitis, (my appendix burst before the surgery), so I was in the hospital for 10 days and my body was under probably the most severe stress it has ever been under. Cut to three months later, after recovery, I decided to put henna in my hair for the first time. About 1.5 weeks later, I started noticing significant hair fall in my brush and in the shower. I wasn't pulling out complete clumps of hair, but it was way more than I usually do, and it was coming from the root (follicle attached.) I recently learned that you can experience telogen effluvium about 3 months after having surgery, and that hair loss makes complete sense given the timing, but I also want to know if henna can also cause hair fall? It's hard to know what is causing it because the timing align with both the surgery and when I put henna in my hair. I would like to continue to put henna in my hair, but if that is the cause of my hair fall, I don't want to lose even more hair. Any thoughts or advice?? Thank you!