I'm really sorry to hear about your condition, which I assume is triggered by the sight of sharp object/edges.The red spiky theme makes me feel unpleasant and a bit sick when I play this game. It’s actually quite nauseating for me to look at. If you could change it, I think it would make your game more appealing and easier to enjoy. But hey, I'm just saying it— just trying to give feedback.
Unfortunately, the "spiky" transitions are part of the theme of the story (another example would be if you've played Starcraft 1 and compare between terran and zerg UI theme). The story will also contains some... images/description that could be disturbing to some. (sharp objects; small, crawling critters)
Personally, I would probably recommend you not to play this game due to your condition, but I'm glad you gave it a try, even if you dislike it.
Thanks!