I'm leery of headaches behind eyeballs; I mean I get them and 99% of the time it is an on coming migraine with some eye strain but the one time I went to the eye doctor and found out bad news. Now I tell everyone "go get checked"
I had a throbbing headache behind my right eyeball for days, I went to the eye doctor and found out I have macular degeneration in both eyes. Plus small cataracts. I was 19.
THIS DOES NOT HAPPEN TO EVERYONE, you will be fine.
ETA: For real, I'm over cautious with it now. I would always get headaches behind my eyes and that one time I went and found that out, I still get the headaches and they usually result in an ocular migraine. But I do tell people who get pain behind their eyes or headaches, to go get checked at some point, just a normal eye exam to rule anything out eye related beyond strain.