Pain behind eye (worse with cold), could it be sinus issues?

I have had severe pain behind my left eye since February. It is worst when I use the computer, drive, or try to read things from afar (essentially anything requiring me to use or strain my eyes). No other symptoms. The pain goes away when I exercise. After seeing a number of ophthalmologists without finding anything, I received a CT scan, which came back clear. I went to an ENT, who did not do anything because the CT was clear. She referred me to a neurologist, who had nothing to say.

I had a bad cold about a month ago, and during the time when my cough and runny nose was at its worst, my pain was a lot worse than normal. I also have a slightly runny nose in general (I have to carry tissues around with me).

Could I still have problems with my sinuses, even if the CT came back clear? I have ruled out just about everything else, and it seems like a sinus condition would perfectly match the location of my pain (it's generally right behind the top part of my cheekbone, encompassing the lower back of my eye socket). I've read a couple stories of people whose CT scans came back clean, but they still had mucus or thickened sinus walls or something.

I am an 18 year old male. Any help would be appreciated. Thank you!