Tell your doctor, get some help from your mom a few hours a week, call on a teenate Mother's Helper, try to get some rest if you can. It sounds like pregnancy hormones and exhaustion.
My first 2 kiddos are 1 yr and 16 days apart. I remember days where I would just hide and cry because I didn't know how I was going to do it with both of them but it's been 1.5 yrs and everyone is still alive and sane! :-) Prego hormones can seriously suck and unfortunately just be aware that they won't magically disappear once the baby is born. I have put myself in time out on many occasions. Just a couple minutes in my room with the door shut crying, simply breathing, etc
I'm expecting my third right now and am going through the same thing again too - this will make 3 under 3! It never helps when ppl offer the "idk how your gonna do this! Comment. But def seek out a helping hand. My mom watches my kids 3 days a week - I work 2.5 and the rest of that third day I run errands or just simply enjoy the peace and quiet. Even of you could get someone to watch the little ones for a couple hrs one day a week trust me when I say it makes a world of difference. And don't let guilt sway you on this. Taking care of yourself/having a little me time is good for the kids too.