Too much pain. Please help.

Firstly, thank you for your time.
I have been dealing with depression on-and-off for a long time now. Last time I got better, I thought it was going to be okay forever now. But sadly depression found me again. I have also indulged in self harming behaviour in the long as well as recent past.
So after more than a year, I’ve been put back on treatment.
Since the past few days I’ve been feeling very agitated. I am unable to explain what I am feeling exactly. But the closest I can get to it is that my mind feels too agitated and pained. I feel like I am going crazy. I have also been having self-harm thoughts because I think I am not being able to deal with the unsettled state of my mind. I just feel very helpless and alone. I just want to know if anyone can relate to any of this and if anyone can possibly explain to me what is exactly happening and why.
Also, I feel like I’m falling apart. I feel like I’m dying inside. And my head feels so messed up right now. I feel like I’m going crazy. I can’t even explain what exactly is up. There is just SO MUCH pain. The emotional pain and anguish is so bad that it’s manifesting itself physically. Every nerve of my body aches. And the physical aspect I can still deal with. But there is just too much pain right now, too much. And it’s just too much for me right now. I’ve spent the night crying hysterically and I can’t deal right now.

Please is there someone, anyone that can talk to me right now? I need it so badly.

I am sorry for causing you trouble and I am grateful to you for giving me your valuable time.

Once again, thank you so much for your time and efforts. I appreciate it very much. I hope today treats you wonderfully.