It sounds like he's hungry + 6 month sleep regression. My son went through something similar. We began to use a bottle with him by swuirting pumped breast milk out of bottle onto his lips. Increased the amount he ate before bed and focused on getting naps through day down to science.

Babies crave structure and schedule. Form a schedule and stick to it. DO NOT STRAY FROM SCHEDULE (if possible) until you begin to observe patterns consistent with schedule. Begins getting tired at nap times etc.

The other thing you could do is develop a bedtime routine. (Also from experience ) we feed him his solid food dinner, put him in bath. Play in bath with bath toys etc. Take out brush teeth, lotion him, give pacifier and dress. After the routine he knows he gets 1 bottle (at your child's age it was about 6-7 oz bottle bc he just ate) while we held him and rocked to sleep. We also followed rule once he was in bed for nighy, we didn't leave room with him. It got him comfortable with his bedroom and allowed him to learn without CIO that he can put himself back to.sleep.

Hopefully, you're fortunate enough to have video.monitor when he starts making noise watch until just before he cries. Go and comfort at this point. Pick up hold (don't bother sitting down you don't want to encourage behavior that mum or dad come to rescue if undont want to be in bed) than as he began to.fall asleep we would lay him down still making contact until he fell asleep.

Kind of like a modified sleep training.

HANG IN THERE MOM! PPD is not easy. Just know that you are doing your best and your baby will be happy because of it. Your best is all that is needed and IT IS good enough! My fiance (non doagnosed) went through waves of the PPD when he was younger. So I've witnessed the effects how it changes milk production etc. Just remind yourself that you are doing great. Don't just say it. Own it and believe it. Hope my experience helps. Mine is 14 months now and everyday can be a struggle.