I've had head pressure for a few weeks and now have been having pain behind my eyes and it hurts underneath my eyes as well. eyes have felt dry too?

Head pressure: See a doctor/urgent care /ER within next 24 hours. Persistent headaches can be due to sinusitis which needs treatment with antibiotics, migraines or more serious brain issues like pseudotumor cerebri, autoimmune conditions, subclinical herpes simplex I infection, lyme disease,glaucoma, rarely aneurysms( rare at your age) tumors.

See your doctor: You should see your doctor to have an evaluation. Allergies could be responsible for your symptoms; however, without being seen it is impossible to say with certainty. You physician can determine if any further evaluation or testing is necessary.