Hello everyone! I’m having some problems, mentally. I was wondering if you guys can suggest any helpful ways for me to get better.

I’m a 20 year old college student. Ever since my niece was born the last string in my brain snapped.( don’t get me wrong I love my niece)
I was born in a family where I have to take care of all family need and my own needs. I am responsible for all family matters (making appointments for doctors for my parents and niece and etc. be there to translate, and call into any company if there is soemthing wrong with the bill). I also is taking 17 credits in college, and working 3 jobs and all are 12 hour shifts. After my niece was born, my brain started breaking down (I’m guessing from the crying at night, since I take care of her too). I’ve been losing sleep, not being able to concentrate in school and always tired at work. My grades have been dripping steadily. I’m just in despair. I feel depress more and more for no reason, although I do recover fast but it still feels horrible.

Please, can anyone suggest anything that will help? Like self care of any sort

Well sounds like classic burnout to me. Try consulting a doctor, a counselor, a therapist or all of them.

My points of advice here is that it is okay to be selfish and look after yourself first. You don't help anyone if you are dead.

And no you are not crazy. Burnout is a kind of depression and depression is a mental desease (a very deadly one) that requires treatment.

Also I am not a doctor, I don't know you and I don't want to give a diagnosis here. There are people out there that are more suited for that.

Definitely mention it to your doctor at least. >>2 already touched on the mental health aspect, but later down the line you'll start having physical health problems because of constant stress. Please take care of yourself before you reach the breaking point. Talking about it with people (professionals and trusted non-professionals) should help, but I think that like >>2 said, it's okay to be selfish. Sometimes it's necessary. You have to look after yourself, so that you can give your loved ones 100% instead of 20%.

I don't know if this is common to other schools, but my school's Student Health Services run de-stressing programs. Like yoga and ice cream socials and stuff? They also have some self-help resources online for stress, anxiety, depression, etc. Here's the link if you'd like, pretty sure you could look at other schools' mental health services too:
https://counseling.uconn.edu/anxiety-stress/