Counterpoint: phones have been shown to warm up brains (1), and it is hardly surprising that amongst the billions of phone users some experience pain/headache from heat (perhaps also indirectly from blood vessel dilation?). So it is hardly surprising for OP to have such an experience.
There is a big causal step between "phones slightly warm brains" and "that causes headaches".
Fortunately we don't need to rely on the fact that it would be “hardly surprising” because there is good quality empirical evidence disproving the relationship.
> There is a big causal step between "phones slightly warm brains" and "that causes headaches".
> Fortunately we don't need to rely on the fact that it would be “hardly surprising” because there is good quality empirical evidence disproving the relationship.
I wish people/you would either be more open minded or at least do a quick Google search. Literally searching for "brain heating headache" got these results which suggest that there is evidence showing a possible relationship. I am not even sure if this conversation is in good faith anymore.
1.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5952570/#:~:tex.... (Quickly googled result, I'm sure there are better results)