having a meltdown

So my baby is now 6 weeks and 6 days, and last week we went to the doctor and was told she had acid reflux (she's been super congested, cold symptoms, cries when she's laying flat, threw up, etc) and they prescribed her Zantac in syrup form and I've been giving it as directed, it's been nearly a week and I've noticed no difference and now she is becoming even more fussier😫 she will ONLY fall asleep on my chest and when she is trying to fall asleep she rubs her face on my chest side to side and then starts crying, she's whimpering when she eats spiratically, crying after she eats for a little while and can't seem to get comfy. Then I was also told to go down to 3 oz every 4 hours (bottle fed) and she was getting 4 oz, but the doctor said she gained nearly a pound in a week which I guess isn't good? Idk. Well she screams unless I give her 4oz and now it's every 3 hours. She has barely slept any at all during the day and here we are at 1 am and I just wanna scream of how sleep deprived I am. Can't call the ped till the morning what do you think is going on?😔