headache due to teething

hi,here wanna talk about my son teething,kelvin is now 4month plus,reaching 5month next week...since he reach to this age i really having headache due to his teething.he always like to cry out his throat all over night...and u know wat....he only cry in the middle of night,is it the pain only start at night?? i was really having a nightmare few days ago..so i took him to clinic...n doc given me gel to massage baby gum to relieve pain...ya its work...but only for 15 mins....he start crying again after 15mins...i feel cant do anything for him to relieve to pain..i try so many method like give frozen teething toy to his mouth....grape water...but all doesnt seem to work...

i really having hard time when need to wake up early n go to work,coz i dont get to sleep at night...how long will this pain last...dont tell me till all his teeth comes out....ohhhh nooo...i cant take it...anyone can help me...