Welcome to HCM.
You have not mentioned your age.
Since your doctor has ruled out sinusitis
, most likely your constant staring into the lap top screen must be putting your eyes into lot of strain, resulting in discomfort or pain in the forehead and eyes, what you describe as pressure.
It would be a good idea to get your eyesight checked for visual acuity. If there is no problem with your eyesight, avoid constantly looking into the computer screen, take frequent breaks and look around in the surrounding area or close your eyes for a couple of minutes and relax and don't sit with your lap top, in darkened areas. While working on computer, there should be diffuse light in the room.
Forget about brain tumours, and cultivate positive attitude.
Wish you all the best.