Ppd?

I have been feeling vary down and not happy with life lately. I have a 3 year old and a 7 month old. I had ppd with my 3 year old but it was 7 weeks after not 7 months after. My 7 month old cries non stop all day whenever she's not being held, I just get so overwhelmed sometimes and I feel like I want to just put her in the crib close the door and leave her there just to get a min to think. I cry almost daily. I feel like such a bad mom sometimes! I think I might go to talk to a tharapist I just want to know if anyone thinks its ppd or not since she's 7 months and I got it so soon after my 1st daughter.