Depression after migraine

I've had migraines for most of my life, I was diagnosed when I was 10 but over the past 5 years or so I've noticed sometimes after or during a migraine I start to get really depressed. This always made sense to me because being in constant pain is exhausting and frustrating. This past year I started Botox treatments and after my last injection about 3 months ago I have noticed a very significant improvement and I'm starting to finally feel optimistic about something that can help me. It feels like I've come out of this horrible pain fog, it's not perfect, I still get around 8 migraines a month but they're manageable and it's not constant pain like it was before. The strange thing is that now that I'm starting to feel better you would think my quality of life should improve, instead I find I'm still getting bouts of depression, it comes and goes and I can't seem to put my finger on what it is that's causing it. I've talked it out,I've tried self reflection, I've tried making changes in my life but nothing seems to be helping. Has anyone else experienced anything like this? Am I mourning the loss of my migraines? I mean that would be completely ridiculous, I HATE migraines but I just can't seem to figure out what is causing this.