Oh love, this is awful. My eldest cried like this for the first 3 months, but I was lucky and it relented then and she became a happy baby. So I do know a little of what it's like, I really feel for you. I didn't bond with her for a long time, I hated my life and was very close to walking out and never coming back on many many an occasion. ADs helped a lot.
I think you need a plan. How about this.
Step 1; can anyone take the baby and toddler for you today, for at least 5 or 6 hours? Husband, MIL etc? You need some peace and quiet to gather your thoughts and step back a little. Don't be afraid of telling them how necessary it is. If any of my friends asked I would do this for them.
Step 2, GP, emergency appointment tomorrow morning. Tell them what you have said here. Tell them your history, how you are feeling and that you NEED support now. No more forgtten prescriptions. Take your DH if you can. He can come in for moral support initially and then take the baby out so you can speak to the GP in peace.
Step 3, urgent call to HV first thing in the morning. Your DH could do this for you. Explain what's happened and that you feel near crisis, and that they need to come round and help put some support together for you.
I'd also say you need to be referred to a paediatrician to get to the bottom of the issues with your baby.