4 1/2 month old baby boy?

my son is now 4 1/2 months old. He is generally a happy baby. but sometimes it seems like when he is upset he really gets upset. like screaming that hurts the ear. I know today he did it when he got over tired. and he fought sleep for two hours. but everytime i try let him nap he only naps on me. never alone. and if i lay him down he cries five mins later like im hurting him. lately he has been really fighting sleep. he wont take his nuk. its like he knows that i want him to sleep. but if i let him stay awake he will miss a nap and then really let me have it. its to the point i cant really enjoy myself anywhere but home cuz of his crying. its very harsh sounding and the doctors already ruled out colic. now he has been sleeping through the night since about two months old. which i am blessed with. and his schedule usually goes wakes up between 6-730 a bottle of formula and rice cereal on the side. awake for about an hour very happy. then as soon as nap time comes about a half hour later he fights it. but eventually loses and falls asleep but i have to hold him or he wont sleep at all. then wakes up around 930 plays for a bit. 1030 a bottle and then an hour later a nap. 130 a bottle and i just recently started him on applesauce. doctor said it was okay. he is over 16 lbs now and almost 5 months. then a nap. his naps can last from 15 min-30 min. sometimes an hour and then another bottle at 430/500 and then try bed by 8 but fights it very hard. so hes usually out around 9 930. i just need some guidence. now i know im supposed to get on a schedual and its hard right now. im working. my fiance is working and they are diff schedules and not everyone follows the schedule and sometimes he doesnt. and yes i do give him a bath to calm him down before bed but it doesnt work. ive done about everything i can. and i just want to know if this is a faze. how long will it last. i just want my baby boy to be happy. and i know he is. but i hate seeing him cry like that. i just need some motherly advice and this is my first baby. thank you