It feels like there's water in my ear, but there isn't? why is this?

Maybe hearing loss: You should see a specialist and get a hearing test. This may be a symptom of hearing loss.

Check if Wax Buildup: I agree with Dr. Gorup. Another thought is that wax-buildups can cause you to hear abnormal sensations (whooshing sound, hearing your pulse in that ear, crackles). This is especially likely if you use Q-tips, earplugs, ear buds, etc. Seeing your primary care doctor for an examine,will determine if wax is the cause If the ear exam is normal, and you have no evidence of a sinus infection, see ENT