Lie down with ice packs on back of neck and over eyes for 10-20 minutes. Repeat as necessary. Pound 4 ibuprofen every couple hours, switch with Tylenol, repeat as necessary (flexeril works wonders too).
Figure out what you’re doing wrong and change your posture. That shit sucks and can lead to the worst migraine clusterfuck that will put you down for days. People mock phonefags but it has its advantages.