my daughter is 4 months old. she is my second. this is my first time breastfeeding and ive made the mistake i guess of feeding her to sleep.

no exaduration, for 4 f-ing weeks on sunday straight, shes woke me every 47 minutes at night EVERY NIGHT. i am beyond exhausted. on wednesday she had her 4 month immunizations and her pedi suggested the reason for this is bc i feed her to sleep and now she cant self soothe. she instructed me to use the "cry it out" method. so for the past two days, today included, ive tried to implement this into our routine. i put her down drowsy but awake. leave for 5 minutes. come back, give her her soother, sing a song, rub her head, leave for 20. come back same thing then leave for 15. etc adding 5 minutes each time. this is terrible. she gets so upset. i dont know what to do but I CANT KEEP WAKING EVERY 45 MINUTES! i am going to go crazy pls help.