I don't understand

It is the absolute worst and utterly confusing feeling in the world to love my baby so much but to not want to be here at the same time. I feel horrible that I feel this way. I had my baby a month ago and it's been the best thing in the world it's what i always wanted...but recently I've been slipping again and it scares the shit out of me. I don't have an appetite at all but I need to eat so he can eat, i feel numb sometime, my body always hurts I'm so stressed and I just feel like shit. I have an amazing husband but I don't understand why I feel so bad. The worst thought I've had so far is that if I were gone my baby wouldn't have known me and then it wouldn't be so bad. I know I should talk to a dr but they would probably put me on meds and I've been on them before and it made feel worse and I'm really scared of that. I'm just really confused and don't know what to do. This shit sucks and I'm tired